Nova LMC 2009a as observed with XMM-Newton, compared with

MNRAS 000 1ndash23 (2019) Preprint 13 May 2021 Compiled using MNRAS LATEX style file v30

Nova LMC 2009a as observed with XMM-Newton compared with othernovae

Marina Orio12 Andrej Dobrotka3 Ciro Pinto4 Martin Henze5 Jan-Uwe Ness6

Nataly Ospina78 Songpeng Pei9 Ehud Behar10 Michael F Bode11

Sou Her1 Margarita Hernanz1213 and Gloria Sala1314

1 Department of Astronomy University of Wisconsin 475 N Charter Str Madison WI 537042 INAFndashOsservatorio di Padova vicolo dellrsquo Osservatorio 5 I-35122 Padova Italy3 Advanced Technologies Research Institute Faculty of Materials Science and Technology in TrnavaSlovak University of Technology in Bratislava Bottova 25 917 24 Trnava Slovakia4 INAF-IASF Palermo via Ugo la Malfa 153 90146 Palermo Italy5 Department of Astronomy San Diego State University San Diego CA 92182 USA6 European Space Astronomy Agency (ESA) European Space Astronomy Center (ESAC) Camino Bajo del Castillo sn

28692 Villanueva de la Canada Madrid Spain7 Department of Physics and Astronomy Padova University via Marzolo 3 35131 Padova8INFN Sezione di Padova Via Marzolo 8 35131 Padova Italy9 Department of Physics and Astronomy Padova University vicolo Osservatorio 3 35122 Padova Italy10 Department of Physics Technion Haifa Israel11Astrophysics Research Institute Liverpool John Moores University IC2 Brownlow Hill Liverpool L3 5RF UK12Institut de Ciencies de lrsquo Espai (ICE-CSIC) Campus UAB c Can Magrans sn 08193 Bellaterra Spain13 Institut drsquo Estudis Espacials de Catalunya cGran Capita 2-4 Ed Nexus-201 08034 Barcelona Spain14 Departament de Fısica EEBE Universitat Politecnica de Catalunya BarcelonaTech Av drsquo Eduard Maristany 10-14

08019 Barcelona Spain

Accepted XXX Received YYY in original form ZZZ

ABSTRACT

We examine four high resolution reflection grating spectrometers (RGS) spectra of the February 2009 outburst of

the luminous recurrent nova LMC 2009a They were very complex and rich in intricate absorption and emission

features The continuum was consistent with a dominant component originating in the atmosphere of a shell burning

white dwarf (WD) with peak effective temperature between 810000 K and a million K and mass in the 12-14 Mrange A moderate blue shift of the absorption features of a few hundred km sminus1 can be explained with a residual

nova wind depleting the WD surface at a rate of about 10minus8 M yrminus1 The emission spectrum seems to be due to

both photoionization and shock ionization in the ejecta The supersoft X-ray flux was irregularly variable on time

scales of hours with decreasing amplitude of the variability We find that both the period and the amplitude ofanother already known 333 s modulation varied within timescales of hours We compared N LMC 2009a with other

Magellanic Clouds novae including 4 serendipitously discovered as supersoft X-ray sources (SSS) among 13 observed

within 16 years after the eruption The new detected targets were much less luminous than expected we suggest that

they were partially obscured by the accretion disk Lack of SSS detections in the Magellanic Clouds novae more than

55 years after the eruption constrains the average duration of the nuclear burning phase

Key words X-rays stars stars cataclysmic variables novae N LMC 2009a galaxies individual LMC

1 INTRODUCTION

Classical and recurrent novae (CNe RNe) are now routinelydiscovered in other galaxies of the Local Group offering use-ful terms of comparison of the nova phenomenon in ambientswith different metallicity and star formation history Knownnovae in the Magellanic Clouds are not numerous due to thesmall mass of the two galaxies but they occur in an envi-

E-mail orioastrowiscedu

ronment of much lower metallicity than the Galaxy and atrelatively close distance only about 5 times as high as thefarthest luminous Galactic novae well studied in recent years(for instance the RN U Sco is at 12plusmn2 kpc distance seeSchaefer et al 2010)

11 Nova LMC 2009A

Nova LMC 2009a (also N LMC 2009-02 in the notation in-cluding the outburst month) was discovered on 2009 February

copy 2019 The Authors

2 M Orio et al

05067 UT by Liller (2009) and spectroscopically confirmedby Bond et al (2009) It was later identified as a RN co-inciding with N LMC 1971b (Bode et al 2016) RN are theones recurring on human time scales although the models in-dicate that all outburst recur (ie Prialnik 1986) An opticalspectrum obtained in outburst by Orio et al (2009) showedprominent emission lines of H He and N so this nova is aHeN one in the classification scheme of Williams (1992) likethe other RNe we know Orio et al (2009) reported a largeexpansion velocity with the full width at half maximum ofthe Hα line slightly above 4200 km sminus1 Additional spectraobtained by Bode et al (2016) showed expansion velocitiesderived from different lines and at different phases between1000 and 4000 km sminus1 Coronal line emission before day 9indicated shocks in the ejecta The initial decay was fast andthe time t3 for a decay by 3 magnitudes lasted from 104days in the V band to 227 days in the infrared K The timet2 for a decay by 2 magnitudes ranged from 5 days (V filter)to 128 days (K filter) These parameters are pertinent to aclassification as a ldquovery fastrdquo nova (Payne-Gaposchkin 1964)

By comparison with the grid of nova models by Yaronet al (2005) the characteristic parameters of the outburst(recurrence time of 38 years velocity reaching 4000 km sminus1t3=114 days in the V band amplitude of about 9 mag in V)place the nova the highest WD mass range (14 M) with arather young and hot WD at the start of accretion and massaccretion rate m of a few 10minus8 M However the models in-clude only a constant mass accretion rate m which may notbe the case in some novae and probably not for RN whoserecurrence time has been observed to vary (while the envelopemass accreted to trigger the burning outburst is expected toremain the same)

Bode et al (2016) identified the progenitor system theoptical and infrared magnitude in different filters and thecolour indexes are best interpreted with the presence of a sub-giant feeding a luminous accretion disk Modulations with aperiod P=12 days most probably orbital in nature wereevident in the UV and optical flux since day 43 (Bode et al2016) Two other RNe with orbital periods of the order of aday and sub-giant evolved secondaries are the Galactic novaeU Sco and V394 CrA There is also evidence that also a thirdRN V2487 Oph hosts a sub-giant although its orbital periodhas not been measured yet (Strope et al 2010) Other novasystems with suspected subgiant secondaries and day-longorbital periods are KT Eri (also a candidate RN but so farwithout previous known outbursts Bode et al 2016) HV Cet(Beardmore et al 2012) and V1324 Sco (Finzell et al 2015)

Luminous CNe and RNe are monitored regularly with Swiftin UV and X-rays It is known that all nova shells emit X-raysin outburst (eg Orio 2012) although they are not usuallyluminous enough to be detected at LMC distance Howeverwhen the ejecta become optically thin to soft X-rays thephotosphere of the WD contracts and shrinks to close to pre-outburst dimension (Starrfield et al 2012 Wolf et al 2013)while CNO burning still occurs close to the surface with onlya thin atmosphere on top for a period of time ranging fromdays to years (Orio et al 2001 Schwarz et al 2011 Page et al2020) Because the WD effective temperature Teff is in the150000 K to a million K range the WD atmosphere peaks inthe X-ray range or very close to it and the WD detected asa luminous supersoft X-ray source (SSS) observable at thedistance of the Clouds also thanks to the low column density

Strengthening of the He II 4686A line in the N LMC 2009aspectrum preceded the emergence of the central WD as asupersoft X-ray source (hereafter SSS) observed in X-rayswith the Swift X-Ray Telescope (XRT) since day 63 TheSSS initially was at lower luminosity but became much moreluminous around day 140 The following X-ray observationsindicated an approximate constant average luminosity (al-beit with large fluctuations from day to day) until aroundday 240 of the outburst The SSS was always variable peri-odically and aperiodically and clear oscillations with the 12days period were observed (Bode et al 2016) with a delay of028P with respect to the optical modulations

Not all novae are sufficiently X-ray luminous to be studiedwith the gratings in detail especially if they are as far as theMagellanic Clouds and we did not want to miss the occasionof the X-ray luminous Nova LMC 2009 so in addition to SwiftX-Ray Telescope (XRT) (Bode et al 2016) XMM-Newtonwas used for longer exposures and high spectral resolution

2 THE OBSERVATIONS

The rise observed with the Swift XRT prompted two obser-vations in the Director Discretionary Time (DDT) requestedby W Pietsch 90 and 165 days after the optical maximumobserved on 2009 February 6 (Liller 2009) In July of 2009the nova was sufficiently X-ray bright to trigger also two pre-approved target of Opportunity (TOO) observations awardedto PI M Orio These exposures were done respectively days197 and 229 after the optical discovery at the observed opti-cal maximum All four XMM-Newton observations are listedin Table 1 While partial results were presented in Orio et al(2013a 2017) this paper contains the first comprehensiveanalysis of all the data

The XMM-Newton observatory consists of five different in-struments behind three X-ray mirrors plus an optical mon-itor (OM) and all observe simultaneously For this paperwe used the spectra from the Reflection Grating Spectrom-eters (RGS den Herder et al 2001) and the light curves ofthe EPIC pn and MOS cameras The calibrated energy rangeof the EPIC cameras is 015-12 keV for the pn and 03-12keV for the MOS The RGS wavelength range is 6-38 A cor-responding to the 033-21 keV energy range Table 1 showsthat in the first two observations the EPIC cameras were usedin imaging mode the pn detector was ldquosmall window moderdquoto mitigate pile up and the medium filter was used while theMOS was used with the ldquosmallrdquo frame and the medium filterThe set up of the third and fourth observation was the samewith larger MOS2 window size and with the thin (instead ofthe medium) filter for both MOS

The EPIC pn and MOS detectors were used to ex-tract light curves with the XMMSAS (XMM Science Anal-ysis System) task XMMSELECT after applying barycen-tric corrections to the event files choosing only single-photon events (PATTERN=0) in the eventsrsquo files A refer-ence for this and the other XMMSAS tasks mentioned be-low is httpsxmm-toolscosmosesaintexternalxmm_

user_supportdocumentationsas_usgUSGpdf The re-sulting source light curves were corrected for background vari-ations using the XMMSAS task epiclccorr Because therewas essentially no emission above 08 keV we used only theRGS with their high spectral resolution for the spectral anal-

MNRAS 000 1ndash23 (2019)

Nova LMC 2009a with XMM-Newton 3

15 20 25 30 35

Wavelength (Angstrom)

Figure 1 The RGS spectra of Nova LMC 2009 in units of measured flux versus wavelength observed on days 90 (2009 May in red) 165

(2009 July in blue) 197 (2009 August grey) and 229 (2009 September purple)

Table 1 XMM-Newton observations of Nova LMC 2009

ObsID Exp timea Dateb MJDb Dayc pn MOS1 MOS2

(ks) (UT) (d)

0610000301 377 2009-05-0643 245495743 904 thinsmall mediumsmall mediumsmall

0610000501 581 (400) 2009-07-2004 245503204 1649 thinsmall mediumsmall mediumsmall

0604590301 319 2009-08-2059 245506359 19617 thinsmall thinsmall thinfull

Notes a Exposure time (cleaned of high flaring background intervals and dead time corrected) of the observation b Start date of theobservation c Time in days after the discovery of Nova LMC 2009 in the optical on 2009 February 05067 UT (MJD 54867067 see

Liller 2009)

ysis We extracted the RGS spectra with the XMMSAS taskrgsproc Periods of high background were rejected

3 IRREGULAR VARIABILITY AND SPECTRALVARIABILITY

The averaged fluxed RGS spectra for each of the four expo-sures are shown in the same plot in Fig 1 as fluxed spectraand in units of erg cmminus2 sminus1 Aminus1 All spectra show a lumi-nous continuum and emission lines While in last three obser-vations the count rate level was comparable and the spectrumdid not change very significantly the first RGS spectrum ob-tained in May of 2009 (on day 90 of the outburst) still hada much lower average continuum consistently with the risephase observed with Swift (Bode et al 2016)

In Fig 2 we present the EPIC-pn light curves during the

four exposures because the pn is the instrument with thelargest count rate and the best time resolution In all four ex-posures there was large aperiodic variability the count ratevaried by an order of magnitude on day 90 by a little moreof a factor of 3 on days 165 and by about 60 on days 197and 229 The MOS and RGS light curves of each exposureare modulated exactly like the pn one Despite a moderateamount of pile-up in the pn spectrum the irregular variabil-ity of the source appeared the same in all instruments Wecorrected for pile-up by excluding an inner region and leavingonly the PSF wing and found that pile-up does not affect theproportional amplitude of the irregular variations and lightcurve trend Irregular variability over time scales of hours hasbeen observed at different epochs in the X-ray light curve inseveral other SSS-novae most notably in N SMC 2016 (Orioet al 2018) V1494 Aql (Drake et al 2003) and in one of

4 M Orio et al

Figure 2 The EPIC-pn light curve from top to bottom as measured on days 90 165 197 229 The red horizontal line in the top panelshows the pn cutoff for the averaged ldquolow count raterdquo and ldquohigh count raterdquo spectra shown in the inset in red and black respectively

(note that the RGS count rate varied proportionally to the pn count rate variation)

the early RS Oph exposures (Nelson et al 2008) HoweverRS Oph was observed many times for hours and we knowthat the supersoft X-ray flux stabilized in the later exposuresBefore proceeding with a spectral analysis we examined thespectral variability to assess whether it is connected with fluxvariability

In the top panel of Fig 2 a red line indicates the countrate limit of 6 counts sminus1 measured with the pn chosen forthe intervals in which we extracted high and low count ratehigh resolution RGS spectra on day 90 This is the only expo-sure for which we found strong variability in the strength ofthe spectral features as shown in the inset in the first panelof the figure There is especially a striking difference in the25-28 A range where some emission lines were almost onlypresent when the flux increased significantly for short periodsIn the other observations (days 165 197 and 229) the countrate variability was not matched by a change in the spectralshape of the continuum to which most of the flux variation isdue Also the strength of most emission lines varied less andthe variations mostly followed with the change in the contin-uum Fig 3 shows ldquotime mapsrdquo that is variations of each lineduring the exposures as well as spectra extracted during twovery short intervals of high and low count rate for each ob-servation We found a correlation of the count rate with thestrength of the N VI and N VII lines The absorption edge ofN VII that abruptly cuts the flux below 18587 A did not

vary with the flux level and for this reason we rule out thatthe variability was caused by changes in intrinsic absorptionA likely interpretation of the variability of the continuum fluxis that along the line of sight a partially covering ldquoopaquerdquoabsorber appeared and disappeared In this scenario the WDsurface is for some time partially obscured by the accretiondisk that was not disrupted in the outburst or by large op-tically thick and asymmetric regions of the ejecta Because ofthe irregular variability over short time scales in Nova LMC2009 we favor the second hypothesis and elaborate this ideain the Discussion and Conclusions sections We rule out in-trinsic variations of the WD flux because the nova modelsindicate that burning occurs at a constant rate thus the thinatmosphere above the burning layer can hardly change tem-perature

4 IDENTIFYING THE SPECTRAL FEATURES

Identifying the spectral features for this nova appears muchmore challenging than it has been for other novae observedin the last 15 years (eg Rauch et al 2010 Ness et al 2011Orio et al 2018 2020) We started by examining the strongestfeatures In the spectrum of day 90 we clearly identify twostrong emission features a redshifted Lyman-α H-like line ofN VII (rest wavelength 2478 A possibly partially blendedwith a weaker line of N VI Heβ at 24889 A) and the N VI

Figure 3 Visualization of the spectral evolution within the observations The four panels show the fluxed spectra as function of wavelength

(top left) colour-coded intensity map as function of time and wavelength (bottom left) rotated light curve with time on vertical and countrate on horizontal axes (bottom right) In the top right panel a vertical bar along the flux axis indicates the colours in the bottom left

panel In the top left panel the red (highest) and blue (lowest) spectra have been extracted during the very short sub-intervals marked in

the light curve (bottom right) with shaded areas and bordered by dashed horizontal lines in the bottom left panel The average spectrum isshown in black and the dark blue light curve is a blackbody fit obtained assuming depleted oxygen abundance in the intervening medium

(see text)

He-like resonance line at 2878 A We fitted the two strongerlines with Gaussian functions and obtained a redshift velocityof 1983plusmn190 km sminus1 for the N VII line and consistently avelocity of 1926+220

minus250 km sminus1 for N VI The integrated fluxin these two lines is 123plusmn018 times 10minus13 erg cmminus2 sminus1 and237plusmn018times 10minus13 erg cmminus2 sminus1 respectively

The spectra of the three following dates when the SSS wasat plateau luminosity show a forest of features in absorptionand also some in emission The continua of these spectra ap-pear remarkably similar but many features varied from oneexposure to the next unlike in other novae observed at thepeak of the SSS emission where the absorption features werenot found to change significantly in different exposures donewithin weeks (eg RS Oph V4374 Sgr V2491 Cyg see Nel-son et al 2008 Rauch et al 2010 Ness et al 2011) Wefocused only on the absorption lines that are clearly commonto all the last three spectra In addition to the interstellar ab-sorption lines of O I at 2351 A and N I at 313 A we foundonly five strong common features whose profiles we show inFig 3 The y-axis shows the averaged RGS1 and RGS2 countrate

The line of N VII at 2478 A appears to have a P-Cyg profilein at least two exposures Rather than being a ldquotruerdquo P-Cygit may be due to the superposition of absorption and emissionlines produced in different regions (eg absorption in the WDatmosphere emission farther out in the shell like in U Scosee Orio et al 2013b) The other lines in Fig3 are only in

absorption The first three were already observed at almostthe same wavelength in other novae (Ness et al 2011) andwere marked as yet ldquounidentifiedrdquo We suggest identificationof two of these lines as argon Ar XIII at rest wavelength29365 A and Ar XIV at 27631-27636 A We also proposea tentative identification of the Ca XI (30448 A) and S XIII(32239 A)

In Table 2 we report blueshift velocity broadening velocityand optical depth obtained with these identifications Fits forone of the spectra are shown in Fig 3 in the panels on the leftTo calculate the blueshift velocities we followed the methoddescribed by Ness et al (2010) to determine the line shiftswidths and optical depths at the line center of the absorptionlines for the spectra for the four exposures Following Nesset al (2011) we did not include the absorption correctionbecause it is not important in determining velocity and opti-cal depth The narrow spectral region around each line wasfitted with a function

C(λ)times eminusτ(λ)

where τ(λ) is a result of the fit and is the opacity for eachline We assumed that C(λ) is a linear function for each line inmodelling the continuum We also fitted the N VII emissioncomponent with a Gaussian function

The blueshift velocity is modest compared to other novae(RS Oph see Nelson et al (2008) V4743 Sgr see Rauchet al (2010) V2491 Cyg see Ness et al (2011) N SMC 2016described in Orio et al (2018)) but this nova was observed

6 M Orio et al

2460 2465 2470 2475 2480 2485 2490 2495 2500Wavelength ( )

1000 0 1000 2000 3000(km s 1)

best fit

2750 2755 2760 2765 2770 2775Wavelength ( )

Ar XIV

1500 1000 500 0 500 1000(km s 1)

Ar XIV

best fit

291 292 293 294 295 296Wavelength ( )

Ar XIII

3000 2000 1000 0 1000(km s 1)

Ar XIII

best fit

3020 3025 3030 3035 3040 3045 3050 3055 3060Wavelength ( )

3000 2000 1000 0 1000 2000(km s 1)

best fit

3200 3205 3210 3215 3220 3225 3230 3235 3240Wavelength ( )

S XIII

2000 1500 1000 500 0 500 1000 1500(km s 1)

S XIII

best fit

Figure 4 On the left the profiles of common features observed with the RGS (averaged RGS1 and RGS2) at days 165 (red) 197 (black)

and 229 (blue) On the right in velocity space the same line and the fit for day 229 (N VII) and for day 197 (other plots)MNRAS 000 1ndash23 (2019)

as a SSS at a much later post-outburst time The spread ofblueshift velocity was also evident in V2491 Cyg (see Nesset al 2011)

5 SPECTRAL EVOLUTION AND THE VIABLESPECTRAL MODELS

With the gratings we measure the integrated flux withouthaving to rely on spectral fits like with broad band dataThe flux in the 033-124 keV (10-38 A) range increased byonly 10 between days 165 and 197 as shown in Table 2On day 197 the source was also somewhat ldquoharderrdquo and hot-ter A decrease by a factor of 16 was registered on day 229when the sources had ldquosoftenedrdquo again This evolution is con-sistent with the maximum temperature estimated with theSwift XRT around day 180 and the following plateau withfinal decline of the SSS occurring between days 257 and 279(Bode et al 2016) We tried global fits of the spectra withseveral steps Although we did not obtain a complete statis-tically significant and comprehensive fit we were able to testseveral models and reached a few conclusions in the physicalmechanisms from which the spectra originated We focusedmostly on the maximum (day 197) for which we show theresult with all all models The first steps were done by usingXSPEC (Dorman amp Arnaud 2001) to fit the modelsbull Step 1 The first panel of Fig 5 shows the fit with a

blackbody for day 197 We first fitted the spectrum with theTBABS model in XSPEC (Wilms et al 2000) however abetter fit albeit not statistically significant yet was with ob-tained with lower blackbody temperature 473 eV (almost550000 K) with the TBVARABS formulation by the sameauthors for the intervening absorbing column N(H) This pre-scription allows to vary the abundances of the absorbingmedium and in the best fit we could obtain we varied theoxygen abundance allowing it to decrease to almost zero be-cause an absorption edge of O I at 228 A in the ISM makesa significant difference when fitting a smooth continuum likea blackbody However it can be seen in Fig 5 even the bestblackbody fit is not very satisfactory in the hard portion ofthe spectrumbull Step 2 Assuming as the models predict (eg Yaron et al

2005 Starrfield et al 2012 Wolf et al 2013) and several ob-servations have confirmed (eg Ness et al 2011 Orio et al2018) that most of the X-ray flux of the SSS originates inthe atmosphere of the post-nova WD we experimented byfitting atmospheric models for hot WDs burning in shell Weused the grid of TMAP models in Non Local Thermodynam-ical Equilibrium (NLTE) by Rauch et al (2010) availablein the web site httpastrouni-tuebingenderauch

TMAPTMAPhtml We wanted to evaluate whether the signif-icant X-ray brightening between May and July (day 90 today 165) was due to the WD shrinking and becoming hot-ter in the constant bolometric luminosity phase predicted bythe nova models (eg Starrfield et al 2012) or to decreasingcolumn density (N(H)) of absorbing material in the shell Inseveral novae and most notably in V2491 Cyg (Ness et al2011) and N SMC 2016 (Orio et al 2018) despite blueshiftedabsorption lines that indicate a residual fast wind from thephotosphere a static model gives a good first order fit andpredicts most of the absorption features We moved towardsthe blue the center of all absorption lines by a given amount

for all lines leaving the blueshift as a free parameter in the100-1500 km sminus1 range compatible with the values found inTable 2

Table 3 (for all four exposures) and Fig 5 (for day 197)show the fit with two different grids of models availablein the web site httpastrouni-tuebingenderauch

TMAPTMAPhtml In the attempt to optimize the fit we calcu-lated both the CSTAT parameter (Cash 1979 Kaastra 2017)and the reduced χ2 but we cannot fit the spectrum very wellwith only the atmospheric model (thus we do not show thestatistical errors in Table 3) since an additional componentappears to be superimposed on the WD spectrum and manyfine details are due to it Bode et al (2016) attributed anunabsorbed luminosity 3-8 times1034 erg sminus1 to the nova ejectaAnother shortcoming is that the TMAP model does not in-clude argon Argon L-shell ions are important between 20 and40 A and argon may be even enhanced in some novae (theoxygen-neon ones see Jose et al 2006) Above we have iden-tified indeed two of these argon features that appear strongand quite constant in the different epochs

Model 1 (M1) is model S3 of the ldquometal richrdquo grid (usedby Bode et al (2016) for the broad band Swift spectra) in-cluding all elements up to nickel and Model 2 (M2) is fromthe metal poor ldquohalordquo composition grid studied for non-novaSSS sources in the halo or Magellanic Clouds which are as-sumed to have accreted metal poor material and may haveonly undergone very little mixing above the burning layerThe nitrogen and oxygen mass abundance in model S3 areas follows nitrogen is 64 times the solar value oxygen is 34times the solar value In contrast carbon is depleted becauseof the CNO cycle and is only 3 the solar value

Novae in the Magellanic Clouds may not be similar to thenon-ejecting SSS They may be metal-rich and not have re-tained the composition of the accreted material since convec-tive mixing is fundamental in causing the explosion heatingthe envelope and bringing towards the surface β+ decayingnuclei (Prialnik 1986) The first interesting fact is that adopt-ing the TBVARABS formulation like for a blackbody does notmake a significant difference in obtaining the best fit In factthe atmospheric models have strong absorption edges andfeatures that ldquopegrdquo the model at a certain temperature andare much more important in the fit than any variation in theN(H) formulation especially with low absorbing column likewe have towards the LMC In the following context we showonly models obtained with TBABS (fixed solar abundances)

Both the metal poor and metal enriched models imply avery compact and massive WD with logarithm of the effec-tive gravity log(g)=9 In fact the resulting effective temper-ature is too high for a less compact configuration the SSSwould have largely super-Eddington luminosity Table 4 doesnot include the blue-shift velocity which was a variable pa-rameter but was fixed for all lines it is in the 300-600 kmsminus1 for each best fit consistently with the measurements inTable 2

In Fig 5 we show the atmospheric fits for day 197 Themetal rich model with higher effective temperature appearsmore suitable We note that in the last three spectra whosebest fit parameters are shown in Table 3 the value of the col-umn density N(H) for this model was limited to a minimumvalue of 3 times1020 cmminus2 consistently with LMC membershipThe fact that the metal rich model fits the spectrum bet-ter indicates that even in the low metallicity environment of

8 M Orio et al

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

day 197 N(H)=19 x 10^(21) cm^(minus2) T(bb)=473 eV

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

day 197 N(H)=561 x 10^(20) cm^(minus2) T(eff)=707000 K

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

day 197 T(eff)=983000 K T(apec)=146 eV N(H)=3 x 10^(20) cm^(minus2)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

day 197 N(H)=3x10^(20) cm^(minus2) T(eff)=992000 K

Figure 5 Clockwise from the top left comparison of the RGS fluxed spectrum on day 197 with different models respectively a blackbody

with oxygen depleted absorbing interstellar medium a metal poor model TMAP atmosphere a metal rich TMAP atmosphere and themetal rich atmosphere with a superimposed thermal plasma component (single temperature) in collisional ionization equilibrium See

Table 3 and text for the details

the LMC the material in the nova outer atmospheric layersduring a mass-ejecting outburst mixes up with ashes of theburning and with WD core material The WD atmosphere isthus expected to be metal rich and especially rich in nitrogenHowever the metal rich model overpredicts an absorptionedge of N VII at 18587 A which is instead underpredictedby the ldquohalordquo model This is a likely indication that the abun-dances may be a little lower than in Galactic novae for whichthe ldquoenhancedrdquo TMAP better fits the absorption edges (egRauch et al 2010) The metal-rich model indicates that thecontinuum is consistent with a WD at effective temperaturearound 740000plusmn50000 K on day 90 and hotter in the fol-lowing exposures reaching almost a million K on day 197Although the fit indicates a decrease in intrinsic absorptionafter the first observation the increase in apparent luminosityis mostly due to the increase in effective temperature and weconclude that the WD radius was contracting until at leastday 197

The ldquoenrichedrdquo model atmosphere seems to be the mostsuitable in order to trace the continuum except for the ex-cess flux above 19 A Because the continuum shape of the

atmospheric model does not change with the temperaturesmoothly or ldquoincrementallyrdquo like a blackbody and is ex-tremely dependent on the absorption edges we cannot ob-tain a better fit by assuming an absorbing medium depletedof oxygen (or other element) This is the same also for theldquohalordquo model Therefore the fits we show were obtained allonly with TBABS assuming solar abundances in the inter-vening column density between us and the source

bull Step 3 In these spectra we do not detect He-like tripletlines sufficiently well in order to use line ratios as diagnostics(see for instance Orio et al 2020 and references therein)In the last panel in Fig 5 we show the fit with TMAP anda component of thermal plasma in collisional ionization equi-librium (BVAPEC in XSPECsee Smith et al 2001) Thefit improvement is an indication that many emission linesfrom the nova outflow are superimposed on the SSS emis-sion but clearly a single thermal component is not sufficientto fit the whole spectrum Nova shells may have luminousemission lines in the supersoft range after a few months fromthe peak of the outburst (V382 Vel V1494 Aql Ness et al2005 Rohrbach et al 2009) Such emission lines in the high

20 25 30 35

minus3

2times10

minus3

3times10

minus3

s sminus

1 Aringminus

minus2

Wavelength (Aring)

day 90 T(eff)=737000 K plasma at 50 eV 114 eV 267 eV

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

day 165 T(eff)=915000 K apec plasma at 175 eV 134 eV 55 eV

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

day 197 T(eff)=978000 K plasma at 60 eV 152 eV 169 eV 154 eV 60 eV

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

Figure 6 Fit to the RGS spectra of days 90 (of the ldquohighrdquo period as shown in Fig2) 165 197 and 229 with the composite model with

parameters in Table 4

resolution X-ray spectra of novae are still measured when theSSS is eclipsed or obscured (Ness et al 2013) indicating anorigin far from the central source Shocked ejected plasma incollisional ionization equilibrium has been found to originatethe X-ray emission of several novae producing emission fea-tures in different ranges from the ldquohardrdquo spectrum of V959Mon (Peretz et al 2016) to the much ldquosofterrdquo spectrum of TPyx (Tofflemire et al 2013)

Adding only one such additional component with plasmatemperature keV improves the fit by modeling oxygen emis-sion lines but it does not explain all the spectrum in a rig-orous way The fit improved by adding one more BVAPECcomponent and improved incrementally when a third onewas added The fits shown in Fig 5 yield a reduced χ2 pa-rameter still of about 3 due to many features that are arestill unexplained Also the N VII K-edge remains too strongand this is not due to an overestimate of N(H) since the softportion of the flux is well modeled In Fig 6 and in Table 4 weshow fits with three BVAPEC components of shocked plasmain collisional ionization equilibrium To limit the number offree parameters the results we present in Table 4 were ob-tained with variable nitrogen abundances as free parameter

that turned out to reach even values around 500 for one ofthe components We obtain a better fit if the nitrogen abun-dance is different in the the three components but differentldquocombinationsrdquo of temperature and nitrogen abundance givethe same goodness of the fit We also tried fits leaving freealso the oxygen and carbon abundances leaving the otherabundances at solar values although the fit always convergedwith al least one of these elements enhanced in at least oneplasma component there was no clear further improvementThe best composite fit with ldquofreerdquo nitrogen is shown in Fig 6for all four spectra Some emission lines are still unexplainedindicating a complex origin probably in many more regionsof different temperatures and densities The fits are not sta-tistically acceptable yet with a reduced value of χ2 of 17 forthe first spectrum about 3 for the second and third and 47for the fourth (we note that adopting cash statistics did notresult in very different or clearly improved fits) however thefigure shows that the continuum is well modeled and manyof the emission lines are also explained

bull Step 4 Since we could not model all the emission lineswith the collisional ionization code the next step was toexplore a photoionization code We used the PION model

10 M Orio et al

Table 2 Rest wavelength and observed wavelength velocity broadening velocity and optical depth resulting from the fit of spectral lineswith proposed identification

Ion λ0 λm vshift vwidth τc(A) (A) (km sminus1) (km sminus1)

0610000501

N VII 24779 24746plusmn 0005 minus394plusmn 66 737plusmn 154 00061plusmn 0003424799plusmn 0049 +242plusmn 94

Ar XIV 27636 27615plusmn 0006 minus223plusmn 64 523plusmn 110 00014plusmn 00002

Ar XIII 29365 29288plusmn 0010 minus789plusmn 104 1216plusmn 202 00027plusmn 00003Ca XI 30448 30413plusmn 0008 minus344plusmn 75 746plusmn 117 00021plusmn 00003

S XIII 32239 32200plusmn 0005 minus361plusmn 49 539plusmn 77 00023plusmn 00003

0604590301

N VII 24779 24728plusmn 0006 minus616plusmn 67 470plusmn 106 00025plusmn 00004Ar XIV 27636 27599plusmn 0005 minus406plusmn 52 323plusmn 83 00018plusmn 00004

0604590401

Table 3 Integrated flux measured in the RGS range 10-38 A effective temperature column density and unabsorbed flux in the WD

continuum resulting from the fit with two atmospheric models with different metallicities as described in the text M1 is metal enriched

and M2 is metal poor

Day RGS Flux M1 Te M1 Unabs flux M1 N(H) M2 Te M2 Unabs flux M2 N(H)

erg cmminus2 sminus1 K erg cmminus2 sminus1 1020 cmminus2 K erg cmminus2 sminus1 1020 cmminus2

904 538 times10minus12 738000 129 times10minus11 65 624000 136 times10minus11 571649 808 times10minus11 910000 908 times10minus11 35 784000 908 times10minus10 61

19617 120 times10minus10 992000 906 times10minus11 45 707000 121 times10minus10 56

(Mehdipour et al 2016) in the spectral fitting package SPEX(Kaastra et al 1996) having also a second important aimexploring how the abundances may change the continuumand absorption spectrum of the central source In fact SPEXallows to use PION also for the absorption spectrum Thephotoionizing source is assumed to be a blackbody but theresulting continuum is different from that of a simple black-body model because the absorbing layers above it removeemission at the short wavelengths especially with ionizationedges (like in the static atmosphere) An important differencebetween PION and the other photoionized plasma model inSPEX XABS previously used for nova V2491 Cyg (Pintoet al 2012) is that the photoionisation equilibrium is cal-culated self-consistently using available plasma routines ofSPEX (in XABS instead the photoionization equilibrium waspre-calculated with an external code) The atmospheric codeslike TMAP include the detailed microphysics of an atmo-sphere in non-local thermodynamic equilibrium with the de-tailed radiative transport processes that are not calculated

in PION however with PION we were able to observe howthe line profile varies with the wind velocity and most im-portant to vary the abundances of the absorbing materialThis step is thus an important experiment whose results maybe used to calculate new ad-hoc atmospheric calculations inthe future The two most important elements to vary in thiscase are nitrogen (enhanced with respect to carbon and toits solar value because mixing with the ashes in the burninglayer) and oxygen (also usually enhanced with respect to thesolar value in novae) We limited the nitrogen abundance toa value of 100 times the solar value and found that this max-imum value is the most suitable to explain several spectralfeatures Oxygen in this model fit is less enhanced than inall TMAP models with ldquoenhancedrdquo abundances resulting tobe 13 times the solar value With such abundances and withdepleted oxygen abundances in the intervening ISM (the col-umn density of the blackbody) we were able to reproduce theabsorption edge of nitrogen and to fit the continuum well Itis remarkable that this simple photoionization model with

Table 4 Main parameters of the best fits obtained by adding three BVAPEC components to the enhanced abundances TMAP model andallowing the nitrogen abundance to vary The flux is the unabsorbed one The N(H) minimum value 3 times1020 cmminus2 and the fit converged

to the minimum value in the second and fourth observation We assumed also a minimum BVAPEC temperature of 50 eV

Parameter Day 904 ldquohigh spectrumrdquo Day 1649 Day 19617 Day 22893

N(H) times1020 (cmminus2) 87+38minus18 3 68+42

minus19 3

Teff (K) 736000+11000minus21000 915000plusmn5 000 978000plusmn5 000 907000plusmn5 000

FSSSun times 10minus11 (erg sminus1 cmminus2) 264+152minus071 769+001

minus004 949+020minus017 558+016

minus008

kT1 (eV) 50+8minus0 55+2

minus5 68plusmn8 55+2minus9

Fun1 times 10minus11 (erg sminus1 cmminus2) 071+070minus069 012+005

minus002 583+1100minus250 017+026

minus016

kT2 (eV) 114+22minus18 134plusmn2 152plusmn6 127plusmn8

Fun2 times 10minus12 (erg sminus1 cmminus2) 174+100minus070 329plusmn003 445+600

minus400 193+046minus029

Fun3 times 10minus12 (erg sminus1 cmminus2) 077+100+1757 556plusmn050 446+521

minus400 329plusmn039

Funtotal times 10minus11 (erg sminus1 cmminus2) 360 869 1621 628

Table 5 Main physical parameters of the SPEX BlackBody(BB)+2-PION model fit for day 197 ISM indicates values

for the intervening interstellar medium column density The errors

(67 confidence level) were calculated only for the PION in ab-sorption assuming fixed parameters for PION in emission The

abundance values marked with () are parameters that reached

the lower and upper limit

N(H)ISM 96plusmn04times 1020 cmminus2

00 (ISM) 006 ()

TBB 812000plusmn3020 KRBB 8 times108 cm

LBB 7 plusmn02times 1037 erg sminus1

N(H)1 64+25minus19 times 1021 cmminus2

vwidth (1) 161plusmn4 km sminus1

vblueshift (1) 327+16minus21 km sminus1

NN 100minus7 ()

00 13plusmn2

ξ (1) 4897+50minus30 erg cm

m 184 times10minus8 M yrminus1

ne (1) 285 times108 cmminus3

N(H)2 26 times1019 cmminus2

vwidth (2) 520 km sminus1

vredshift (2) 84 km sminus1

ξ (2) 302 erg cm

LX (2) 11 times1036 erg sminus1

the possibility of ad-hoc abundances as parameters fits thecontinuum and many absorption lines better than the TMAPatmospheric model

To model some of the emission lines we had to include asecond PION component suggesting that the emission spec-

trum does not originate in the same region as the absorptionone as we suggested above Table 5 and Fig 7 show thebest fit obtained for day 197 Due to the better continuumfit even if we seem to have modeled fewer emission lines χ2

here was about 2 (compared to a value of 3 in Fig 6) Theblackbody temperature of the ionizing source is 70 keV orabout 812000 K and its luminosity turns out to be Lbol=703times1037 erg sminus1 and by making the blackbody assumption weknow these are only a lower and upper limit respectively forthe effective temperature and bolometric luminosity of thecentral source (see discussion by Heise et al 1994) The X-ray luminosity of the ejecta is 1036 erg sminus1 or 15 of thetotal luminosity

The value of the mass outflow rate m in the table is not afree parameter but it is obtained from the other free param-eters of the layer in which the absorption features originate(region 1) following Pinto et al (2012) as

m = (Ω4π)4πmicromHvblueshiftLξ

and the electron density of each layer is obtained as

nH = (ξL)(NHfcβ)2

where mH is the proton mass micro is the mean atomic weight(we assumed 115 given the enhanced composition) Ω is thefraction of a sphere that is occupied by the outflowing mate-rial fc is a clumpiness factor and β is a scale length For afirst order calculation we assumed that Ω fc and β are equalto 1 The small radius of the emitting blackbody is compat-ible only with a very massive WD andor with an emittingregion that is smaller than the whole surface The value of mobtained in the best fit is of course orders of magnitude lowerthan the mass loss during the early phase of a nova but theevolutionary and nova wind models predict even a complete

12 M Orio et al

halt to mass loss by the time the supersoft source emerges(Starrfield et al 2012 Wolf et al 2013 eg)

An interesting fact is that we were indeed able to explainseveral emission features but not all It is thus likely thatthere is a superposition of photoionization by the centralsource and ionization due to shocks in colliding winds in theejecta However we did not try any further composite fit be-cause too many components were needed and we found thatthe number of free parameters is too large for a rigorous fitIn addition the variability of some emission features withinhours make a precise fit an almost impossible task

Assuming LMC distance of about 496 kpc (Pietrzynskiet al 2019) the unabsorbed flux in the atmospheric mod-els at LMC distance implies only X-ray luminosity close to 4times1036 erg sminus1 on the first date peaking close to 27times 1037

erg sminus1 on day 197 (although the model for that date in-cludes a 60 addition to the X-ray luminosity due to a verybright plasma component at low temperature 70 eV close tothe the value obtained with PION for the blackbody-like ion-izing source) We note that the X-ray luminosity with thehigh Teff we observed represents over 98 of the bolometricluminosity of the WD Thus the values obtained with thefits are a few times lower than the post-nova WD bolometricluminosity exceeding 1038 erg sminus1 predicted by the models(eg Yaron et al 2005) Even if the luminosity may be higherin an expanding atmosphere (van Rossum 2012) it will notexceed the blackbody luminosity of the PION fit 7 times1037

erg sminus1 which is still a factor of 2 to 3 lower than Edding-ton level Although several novae have become as luminousSSS as predicted by the models (see N SMC 2016 Orio et al2018) in other post-novae much lower SSS luminosity hasbeen measured and in several cases this has been attributedto an undisrupted high inclination accretion disk acting as apartially covering absorber (Ness et al 2015) although alsothe ejecta can cause this phenomenon being opaque to thesoft X-rays while having a low filling factor In U Sco insteadthe interpretation for the low observed and inferred flux wasdifferent It is in fact very likely that only observed Thom-son scattered radiation was observed while the central sourcewas always obscured by the disk (Ness et al 2012 Orio et al2013b) However also the reflected radiation of this nova wasthought to be partially obscured by large clumps in the ejectain at least one observation (Ness et al 2012)

In the X-ray evolution of N LMC 2009 one intriguing factis that not only the X-ray flux continuum but also that theemission features clearly increased in strength after day 90This seems to imply that these features are either associatedwith or originate very close to the WD to which we attributethe SSS continuum flux

bull Step 5 An additional experiment we did with spectral fit-ting was with the ldquoexpanding atmosphererdquoldquowind-typerdquo WTmodel of van Rossum (2012) which predicts shallower ab-sorption edges and may explain some emission features withthe emission wing of atmospheric P-Cyg profiles One of theparameters is the wind velocity at infinite which does nottranslate in the observed blue shift velocity The P-Cyg pro-files becomeldquosmeared outrdquoand smoother as the wind velocityand the mass loss rate increase Examples of the comparisonof the best model with the observed spectra plotted with IDLand obtained by imposing the condition that the flux is emit-ted from the whole WD surface at 50 kpc distance are shownfor days 90 and 197 in Fig 8 in the top panel The models

shown are those in the calculated grid that best match thespectral continuum however that there are major differencesbetween model and observations Next we assumed that onlya quarter of the WD surface is observed thus choosing modelsat lower luminosity but we obtained only a marginally bet-ter match The interesting facts are the mass outflow rateis about the same as estimated with SPEX and the PIONmodel b) this model predicts a lower effective temperaturefor the same luminosity and c) most emission features do notseem to be possibly associated with the ldquowind atmosphererdquoas calculated in the model It is not unrealistic to assumethat they are produced farther out in the ejected nebula animplicit assumption in the composite model of Table 4 andFig 6

6 COMPARISON WITH THE SPECTRA OF OTHERNOVAE

To date 25 novae and supersoft X-ray sources have been ob-served with X-ray gratings often multiple times so a compar-ison with other novae in the supersoft X-ray phase is usefuland can be correlated with other nova parameters While thelast part of this paper illustrates an archival search in X-raydata of other MC novae in this Section we analyse some highresolution data of Galactic and Magellanic Clouds (MC) no-vae bearing some similarity with N LMC 2009

1 Comparison with U Sco The first spectrum (day 90)can be compared with one of U Sco another RN that hasapproximately the same orbital period (Orio et al 2013b) Inthis section all the figures illustrate the fluxed spectra In USco the SSS emerged much sooner and the turn-off time wasmuch more rapid Generally the turn-off and turn-on timeare both inversely proportional to the mass of the accretedenvelope and Bode et al (2016) note that this short timeis consistent with the modelsrsquo predictions for a WD mass11ltm(WD)lt 13 M which is also consistent with the higheffective temperature However the models by Yaron et al(2005) who explored a large range of parameters predictonly relatively low ejection velocities for all RN and thereis no set of parameters that fits a ivery fast RN like U Scowith large ejection velocity and short decay times in opticaland X-rays Thus the specific characteristics of U Sco may bedue to irregularly varying m andor other peculiar conditionsthat are not examined in the work by Yaron et al (2005) Theparameters of N LMC 2009 instead compared with Yaronet al (2005) are at least marginally consistent with theirmodel of a very massive (14 M) initially hot WD (probablyrecently formed) WD

Fig 9 shows the comparison of the early Chandra spectrum(day 18) of U Sco (Orio et al 2013b) with the first spectrum(day 90) of N LMC2009 The apparent P-Cyg profile of the NVII H-like line (2478 A rest wavelength) and the N VI He-like resonance line with (2878 A rest wavelength) is observedin N LMC 2009 like in U Sco with about the same redshiftfor the emission lines and lower blueshift for the absorptionThe definition ldquopseudo P-Cygrdquo in Orio et al (2013b) wasadopted because there is clear evidence that the absorptionfeatures of U Sco in the first epoch of observation were inthe Thomson-scattered radiation originally emitted near oron the WD surface The emission lines originated in an outerregion in the ejecta at large distance from the WD

Figure 7 Fit to the spectrum of day 197 with two PION regions as in Table 5

Apart from the similarity in the two strong nitrogen fea-tures the spectrum of N LMC 2009 at day 90 is much moreintricate than that of U Sco and presents aldquoforestrdquoof absorp-tion and emission features that are not easily disentangledalso given the relatively poor SN ratio U Sco unlike N LMC2009a never became much more X-ray luminous (Orio et al2013b) and the following evolution was completely differentfrom that of N LMC 2009 with strong emission lines andno more measurable absorption features Only a portion ofthe predicted WD flux was detected in U Sco and assuminga 12 kpc distance for U Sco (Schaefer et al 2010) N LMC2009a was twice intrinsically more luminous already at day90 ahead of the X-ray peak although above above 26 A thelower flux of U Sco is due in large part to the much higherinterstellar column density (Schaefer et al 2010 Orio et al2013b) also apparent from the depth of the O I interstellarline U Sco did not become more luminous in the followingmonitoring with the Swift XRT (Pagnotta et al 2015) Giventhe following increase in the N LMC 2009 SSS flux we sug-gest that in this nova we did not observe the supersoft fluxonly in a Thomson scattered corona in a high inclination sys-tem like in U Sco but probably there was a direct view ofat least a large portion of the WD surface

2 Comparison with KT Eri A second comparison shownin Fig 10 and more relevant for the observations from day165 is with unpublished archival observations of KT Eri aGalactic nova with many aspects in common with N LMC2009a including the very short period modulation in X-rays(35 s see Beardmore et al 2010 Ness et al 2015) Fig 10shows the spectrum of N LMC 2009 on day 165 overimposedon the KT Eri spectrum observed with Chandra and the LowEnergy Transmission Grating (LETG) on day 158 (Ness et al2010 Orio et al 2018)

The KT Eri GAIA parallax in DR2 does not have a large

error and translates into a distance of 369+053minus033 kpc 1 The

total integrated absorbed flux in the RGS band was 10minus8 ergsminus1 cmminus2 and the absorption was low comparable to thatof the LMC (Pei et al 2021) implying that N LMC 2009 wasabout 23 times more X-ray luminous than KT Eri althoughthis difference may be due to the daily variability observedin both novae Bode et al (2016) highlighted among othersimilarities a similar X-ray light curve However there aresome significant differences in the Swift XRT data the riseto maximum supersoft X-ray luminosity was only about 60days for KT Eri and the decay started around day 180 fromthe outburst shortly after the spectrum we show here Thetheory predicts that the rise of the SSS is inversely propor-tional to the ejecta mass The duration of the SSS is alsoa function of the ejected mass which tends to be inverselyproportional to both the WD mass and the mass accretionrate before the outburst (eg Wolf et al 2013) The valuesof Teff for N LMC 2009a indicate a high mass WD and thetime for accreting the envelope cannot have been long witha low mass accretion rate since it is a RN The other fac-tor contributing to accreting higher envelope mass is the WDeffective temperature at the first onset of accretion (Yaronet al 2005) This would mean that the onset of accretion wasrecent in N LMC 2009a and its WD had a longer time to coolthan KT Eri before accretion started

KT Eri was observed earlier after the outburst with Chan-dra and the LETG showing a much less luminous source onday 71 after the outburst then a clear increase in luminosityon days 79 and following dates The LETG spectrum of KTEri appeared dominated by a WD continuum with strong ab-

1 From the GAIA database using ARIrsquos Gaia Services

see httpswww2mpia-hdmpgdehomescaljgdr2_distances

gdr2_distancespdf

14 M Orio et al

Figure 8 Comparison of the ldquoWT modelrdquo with the observed spectra on day 90 (averaged spectrum) and day 197 In the upper panels

the condition that the luminosity matched that observed at 50 kpc is imposed assuming respectively for day 90 and 197 Teff=500000

K log(geff)=783 N(H)=2 times1021 cmminus2 m = 2times 10minus8 M yrminus1 vinfin=4800 km sminus1 and Teff -550000 K log(geff)=830 m = 10minus7 Myrminus1 N(H)=15 times1021 cmminus2 vinfin=2400 km sminus1 In the lower panels the assumption was made that only a quarter of the WD surface

is observed and the parameters are Teff=550000 K log(geff)=808 m = 10minus8 M yrminus1 N(H)=18 times1021 cmminus2 vinfin=2400 km sminus1 and

Teff -650000 K log(geff)=890 m = 2times 10minus8 M yrminus1 N(H)=2 times1021 cmminus2 vinfin=4800 km sminus1 respectively for day 90 and 197

sorption lines from the beginning and in no observation didit resemble that of N LMC 2009a on day 90 Unfortunatelybecause of technical and visibility constraints the KT Eri ob-servations ended at an earlier post-outburst phase than theN LMC 2009a ones However some comparisons are possibleFig 10 shows the comparison between the KT Eri spectrumof day 158 and the N LMC 2009 spectrum of day 165 We didnot observe flux shortwards of an absorption edge of O VIIat 186718 A for KT Eri but there is residual flux above thisedge for N LMC 2009a probably indicating a hotter sourceWe indicate the features assuming a blueshift velocity of 1400km sminus1 more appropriate for KT Eri while the N LMC 2009blueshift velocity is on average quite lower The figure alsoevidentiates that in N LMC 2009 there may be an emissioncore superimposed on blueshifted absorption for the O VIItriplet recombination He-like line with rest wavelength 216A

N LMC 2009 does not share with KT Eri or with othernovae (Rauch et al 2010 Orio et al 2018 see) a very deepabsorption feature of N VIII at 2478 A which was almost

saturated in KT Eri on days 78-84 It appears like a P Cygprofile as shown in Fig 4 and the absorption has lower veloc-ity of few hundred km sminus1 Despite many similarities in thetwo spectra altogether the difference in the absorption linesdepth is remarkable The effective temperature upper limitderived by Pei et al (2021 preprint private communication)for KT Eri is 800000 K but the difference between the twonovae is so large that it seems to be not only due to a hot-ter atmosphere (implying a higher ionization parameter) wesuggest that abundances andor density must also be playinga role

3 Comparison with Nova SMC 2016 In Fig 11 we showthe comparison of the N LMC 2009 day 197 spectrum withthe last high resolution X-ray spectrum obtained on day 88for N SMC 2016 (Aydi et al 2018a Orio et al 2018) Theevolution of N SMC 2016 was much more rapid the mea-sured supersoft X-ray flux was larger by more than an orderof magnitude and the unabsorbed absolute luminosity waslarger by a factor of almost 30 (see Table 2 and Orio et al2018) The lines of N VII (rest wavelength 2478 A) N VI

Figure 9 The XMM-Newton RGS X-ray spectrum of of Nova LMC 2009a on day 90 of the outburst (grey) compared in the left panelwith the Chandra Low Energy Transmission Gratings of U Sco on day 18 with the photon flux multiplied by a factor of 10 for N LMC

2009a (red) The distance to U Sco is at least 10 kpc (Schaefer et al 2010) or 5 times larger than to the LMC) so the absolute X-ray

luminosity of N LMC 2009a at this stage was about 25 times that of U Sco H-like and He-like resonance and forbidden line of nitrogenare marked with a redshift 0008 (corresponding to 2400 km sminus1 measured for the U Sco emission features) These features in U Sco

were also measured in absorption with a blueshift corresponding to 2000 km sminus1 producing an apparent P-Cyg profile We also indicate

the O I interstellar absorption at rest wavelength

recombination (2879 A) and C VI (337342 A) seem to bein emission for N LMC 2009a but they are instead observedin absorption for N SMC 2016 The absorption features of NSMC 2016 are also significantly more blueshifted by about2000 km sminus1 in N SMC 2016 The effective temperature inthis nova was estimated by Orio et al (2018) as 900000 Kin the spectrum shown in the figure The comparison showsthat N LMC 2009 was probbaly hotter andor had a denserphotoionized plasma

4 Finally another significant comparison can be made withN LMC 2012 (for which only one exposure was obtained see Schwarz et al 2015) the only other MC nova for whichan X-ray high resolution spectrum is available Despite thecomparable count rate the spectrum of N LMC 2012 shownby Schwarz et al (2015) is completely different from those ofN LMC 2009 It has a much harder portion of high continuumthat is not present in other novae and the flux appears tobe cut only by the O VIII absorption edge at 14228 A Weonly note here that the continuum X-ray spectrum in thisnova appears to span a much larger range than in most othernovae including N LMC 2009a We did attempt a preliminaryfit with WD atmospheric models for this nova and suggestthe possible presence in the spectrum of two separate zonesat different temperature possibly due to magnetic accretion

onto polar caps like suggested to explain the spectrum ofV407 Lup (Aydi et al 2018b)

7 TIMING ANALYSIS REVISITING THE 33 S PERIOD

Ness et al (2015) performed a basic timing analysis for theXMM-Newton observations detecting a significant modu-lation with a period around 333 s The period may havechanged by a small amount between the dates of the ob-servations Here we explore this modulation more in detailalso with the aid of light curvesrsquo simulations Such short pe-riod modulations have been detected in other novae (see Nesset al 2015 Page et al 2020) and non-nova SSS (Trudolyubovamp Priedhorsky 2008 Odendaal et al 2014) Ness et al (2015)attributed the modulations to non-radial g-mode oscillationscaused by the burning that induces gravity waves in the en-velope (so called ε mechanismrdquo but recently detailed modelsseem to rule it out because the typical periods would not ex-ceed 10 s (Wolf et al 2018) Other mechanisms invoked to ex-plain the root cause of the pulsations are connected with theWD rotation If the WD accretes mass at high rate the WDmay be spun to high rotation periods In CAL 83 the oscil-lations have been attributed by Odendaal amp Meintjes (2017)

16 M Orio et al

Figure 10 Comparison the spectrum of N LMC 2009 on day 165 with the spectrum of KT Eri on day 158 with the photon flux of N LMC2009 divided by a factor of 80 In the panel on the left we indicate the lines position with a blueshift by 1410 km sminus1 which is a good fit

for several absorption lines of KT Eri predicted by the atmospheric models (except for O I and N I which are local ISM lines observed

at rest wavelength)

toldquodwarf nova oscillationsrdquo (DNO) in an extremeldquolow-inertiamagnetic accretorrdquo

71 Periodograms

We compared periodograms of different instruments and ex-posures Because the low count rate of the RGS resulted inlow quality periodograms or absent signal we focused on theEPIC cameras despite some pile-up which effects especiallythe pn

In Fig 12 we show and compare all the calculated peri-odograms Even though the reading times were uniform weused the Lomb-Scargle (Scargle 1982) method because it al-lows to better resolve the period than the Fourier transformdue to oversampling We show a larger time interval in theleft insets while the most important features are shown inthe main panels Table 6 summarizes the most significant pe-riodicities with errors estimated from the half width at halfmaximum of the corresponding peaks The periodograms forthe light curves measured on days 90 and 229 do not showan obviously dominant signal in the other observations (al-though as Table 3 shows we retrieved the period in the pnlight curve on day 229 with lower significance) so we did notinvestigate these data further It is very likely that the modu-lation started only in the plateau phase of the SSS and ceasedaround the time the final cooling started For the data of days165 and 197 we found dominant peaks especially strong on

day 197 The dominant signal is absent in the MOS light curveof day 165 but was retrieved instead in the RGS data of thesame date Both periodograms suggest a single signal with adouble structure in the pn that however may be an artifactMoreover the periodicity measured with the RGS data onday 165 is the average of the two values measured with thepn on the same day This may indicate that the amplitude inthe pn light curve is not stable generating a false beat likein V4743 Sgr (Dobrotka amp Ness 2017) The beat causes usto measure a splitting of the peak while the real signal is inbetween (so it may be P4 detected in the RGS data)

The pattern is more complex on day 197 The periodic-ity P3 detected in July is retrieved in all the August lightcurves suggesting that this feature is real and stable More-over the non pile-up corrected and the pile-up corrected pnperiodograms and the MOS-1 periodograms for day 197show the same patterns implying that pile-up in the pn datadoes not strongly effect the timing results We were interestedin exploring whether the non pile-up corrected light curveswhich have higher SN also give reliable results For the day197 observation we compared the results using the pile-upcorrected pn light curve to those obtained for the MOS-1and found that the derived periodicities (P1 and P3) agreewithin the errors Worth noting is the dominant peak P2 inthe non pile-up corrected pn data measured also in the pile-up corrected light curve but with rather low significance Wenote that also many of the low peaks and faint features are

Figure 11 Comparison of the spectrum of N LMC 2009 on day 165 with the spectrum of N SMC 2016 on day 88 with the photon flux of

N LMC 2009 multiplied by a factor of 18 for the comparison

Table 6 Detected periodicities in seconds corresponding to the strongest signals shown in Fig 12 We include a possible periodicity in

the September data of day 229 although the corresponding peak is not by any means as dominant as on days 165 and 197 In each row

we report periods that are consistent with each other within the statistical error

label pn RGS pn pn no-pile-up MOS1 pnDay 1649 Day 1649 Day 19617 Day 19617 Day 19617 Day 22893

P1 ndash ndash 3289plusmn 002 3290plusmn 002 3289plusmn 002 3289plusmn 001P2 ndash ndash ndash 3313plusmn 002 ndash ndash

P3 3335plusmn 002 ndash 3331plusmn 002 3332plusmn 002 3331plusmn 002 ndashP4 ndash 3338plusmn 001 ndash ndash ndash ndashP5 3341plusmn 001 ndash ndash ndash ndash ndash

present in both periodograms but with different power Thisconfirms that pile-up does not affect the signal detection al-though we cannot rule out that it affects its significance

72 Is the period variable

The complex pattern discovered in the light curve of day 197suggests that the period may have varied during the expo-sure We already mentioned the variable amplitude on day165 and reminded that variable amplitude was discovered inthe case of V4743 Sgr (Dobrotka amp Ness 2017) In Appendix1 we show how we used simulations to investigate the possi-bility of variable periodicity and amplitude The conclusionthat can be derived is that models with variable periodic-ity match the data better than those with a constant period

The lingering question is whether different periodicities occursimultaneously or whether instead the period of the modu-lation changes on short time scales in the course of eachexposure We reasoned that if the period varied during theexposures this must become evident by splitting the originalexposure in shorter intervals Therefore we experimented bydividing the day 197 light curve into two and three equallylong segments The corresponding periodograms are depictedin Fig 13 Dividing the light curve into halves shows thatthe first half comprises both dominant signals P1 and P3while the second half is dominated only by P3 We tried afurther subdivision in three parts and found that the firstinterval is dominated by P1 the second by P2 and P3 (with aslight offset) and in the third portion none of the P1 P2 andP3 periods can be retrieved This indicates that the period

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

18May (day 90) Sept (day 229)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

Figure 12 Comparison of periodograms of different instruments

and observations The pile-up corrected pn data (pn no central)were extracted after subtracting the central most piled-up region

of the source The insets on the left show larger period intervals

and the shaded areas are the intervals plotted in the main panelsThe insets on the right show instead a narrower period interval

than the main panels with the August 2009 periodogram plotted

in red

of the modulation was most likely variable during the expo-sure This is probably the reason for which different periodsof similar length were measured in the same periodogram byanalyzing the light curve of the whole exposure time We sug-gest that these periods did not coexist but instead a singlemodulation occurred whose slightly changed during time in-tervals of minutes to hours While Ness et al (2015) foundthat the short-term periodicity may be a recurrent and tran-sient phenomenon here instead our interpretation is that thevariations in amplitude and length of the period sometimesmake it undetectable but most likely it is always present

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

Figure 13 Periodograms for day 197 divided into halves and thirds

The vertical dashed lines indicate the periods P1 P2 and P3 ob-

tained by analyzing the whole exposure at once

8 DISCUSSION N LMC 2009A

Nova LMC 2009 is only one of three novae in the Clouds thatcould be observed with high resolution X-ray spectroscopyThe others were N LMC 2012 (Schwarz et al 2015) and NSMC 2016 (Orio et al 2018) All three novae are luminousand reached a range of effective temperature that can onlybe explained with the presence of a massive WD close to theChandrasekhar limit if we compare the data with models byYaron et al (2005) However a word of warning should begiven concerning the fact the models do not explain all the RNcharacteristics in a very consistent way In fact the ejectionvelocity inferred from the optical spectra exceeds the valuepredicted by the models for a RN with a recurrence period of38 years or shorter this difficulty of modeling RN is a knownproblem A possible explanation is that m has been variableover the secular evolution of these novae if the recurrencetime was longer and m was lower in previous epochs theclosely spaced nova outbursts have only started very recentlyand the material in the burning layer may still be colder andmore degenerate than it would be after many outburst witha very short recurrence time thus causing a larger ejectionvelocity than in the models which assume that the accretedmass is accumulated on a hotter surface

N LMC 2009a was not as X-ray luminous as N LMC 2012and N SMC 2016 N SMC 2016 also remained a much moreluminous SSS for many months Like these and other no-vae observed with the gratings LMC 2009a showed a hotcontinuum compatible with a peak effective temperature ofalmost a million K predicted by the models for a WD massm(WD)gt13 M However the absolute X-ray luminosityestimated by fitting the spectrum in a phase when it con-stitutes over 98 of the bolometric luminosity in N LMC2009 is only a portion of the predicted Eddington luminosityBecause the X-ray flux of this nova was irregularly variableduring all observations over time scales of hours our inter-pretation is that the filling factor in the outflow of the ejectavaried and was subject to instabilities even quite close tothe WD surface never becoming completely optically thin

to X-rays during the SSS phase We suggest that the WDwas observed through a large ldquoholerdquo (or several ldquoholesrdquo) ofoptically thin material that changed in size as the ejecta ex-panded clumped due to instabilities in the outflow becameshocked and evolved This is likely to have happened if thereif the outflow even at late epoch after maximum was nota continuous and smooth phenomenon We note that Aydiet al (2020) explain the optical spectra of novae as due todistinct outflow episodes Also several emission and absorp-tion features of this nova were not stable in the different ex-posures varying significantly over timescales of hours butmostly without a clear correlation with the continuum level

It is remarkable that the nova does not show all the charac-teristic deep and broad absorption features of oxygen nitro-gen and carbon observed in other novae and attributed to theWD atmosphere Some of these features in this nova may bein emission and redshifted but an attempt to fit the spectrawith a ldquowind-atmosphererdquo model by van Rossum (2012) didnot yield a result Perhaps the emission cores originate in theejecta and are not to be linked with the WD as is the casein other novae Although we identified and measured severalabsorption and emission features we came to the conclusionsthat there are overlapping line systems produced in differentregions and with different velocity most of them originatingin the ejected shell through which we observed only a portionof the WD luminous surface

Finally the short period modulation observed in N LMC2009 is intriguing because it varies in amplitude and in pe-riod length over time scales of few hours The value obtainedfor the length of the period is not compatible with against anon-radial g-mode oscillation due to the ldquoεrdquo mechanism dur-ing nuclear burning which is expected to have shorter periods(Wolf et al 2018) The non-stability of the period seems torule out that it is due to the rotation of a WD that has beenspun-up by accretion Yet the very similar short term mod-ulations observed in three other novae in the SSS phase andin CAL 83 a non-nova SSS (see Ness et al 2015) suggeststhat the root cause has to do with the basic physics of nuclearburning WDs

9 ARCHIVAL X-RAY EXPOSURES OF OTHER NOVAEIN THE MAGELLANIC CLOUDS

Table 7 shows details of the pointed and serendipitous X-ray observations of the MC novae in outburst in the last 20years We observe only about two novae a year in the LMCand one every two years in the SMC (see among othersMroz et al 2016) but thanks to the known distance the lowcolumn density along the line of sight and the proximity theMagellanic Clouds provide very useful constraints to studythe SSS phase of novae It is expected that in some caseseven the emission of the ejecta before the onset of the SSScan be detected albeit with low SN Since the advent ofChandra and XMM-Newton three novae including N LMC2009a (2009-02) described here have been observed with theX-ray gratings in high spectral resolution However the X-ray luminosity of novae in the Magellanic Clouds appears tovary greatly as Table 7 shows

Recent Swift observations of N LMC 2017-11a carried onfor 11 months did not yield any X-ray flux detection (Aydiet al 2019) N SMC 2019 was monitored for a few weeks

and only a weak X-ray source emerged after 4 months Therecurrent nova in outburst in the LMC in 2016 and in 2020(previously known as 1968-12a and 1990b) was well followedwith the XRT but it was not X-ray luminous enough forhigh resolution spectroscopy (Kuin et al 2020 Page et al2020) Two other X-ray-detected novae were not luminousenough for the gratings N LMC 2000 (Orio et al 2003a) andN LMC 1995 (Orio et al 2003b) The latter had a long SSSphase between 5 and 8 years In fact it was observed againby us in 2008 with XMM-Newton and no longer detected

XMM-Newton and Chandra typically offer much long ex-posures (several hours versus less than few tens of minutesfor Swift XRT) We explored the archival serendipitous X-rayobservations for MC novae of the last 20 years to search forother possible detections This work was part of Sou Her se-nior thesis project in Wisconsin in 2016 Table 7 shows thatwe found 4 previously unknown serendipitous detections inXMM-Newton deep exposures among 13 novae that wereobserved with these satellites (only two were serendipitouslyobserved with Chandra and six more with with Swift withshallow upper limits) The upper limits on the luminositywere at least about 1035 erg sminus1 for the XMM-Newton expo-sures in Table 7 Observations of novae more than 10 yearsafter the outburst were available in three cases N LMC 2001-08 (11 and 16 years) N SMC 2002-10 (10 and 15 years) NSMC 2005-08 (11 years) and yielded no detections The mostadvanced epoch for which we retrieved an X-ray detectionwas only 5 years and 3 months after maximum

The measured count rates of the serendipitous targets aregiven in Table 7 and the broad band spectra with spectral fitswith TMAP yielding a reduced χ2 value of 13 for N LMC2008 and of about 1 for the other three novae are shownin Table 7 and Fig 14 The SSS flux of the newly detectednovae is much lower than predicted by the models and ob-served in the novae measured with the X-ray gratings Evenif the absolute luminosity value may vary significantly withinthe 90 probability range and is poorly constrained we canrule out that these novae were near Eddington luminosityRather than having observed only the final decline which ispredicted to last for only a few weeks (Prialnik private com-munication) and was indeed observed to take few weeks in RSOph (Nelson et al 2008) we suggest that we detected novaein which the WD was not fully visible and only a small regionof the surface was observed either because of obscuration bythe ejecta or by the accretion disk Given the elapsed post-outburst time longer than a year the latter is much morelikely The value of the column density N(H) inferred in thespectral fits and shown in Table 7 is in fact consisting withno significant intrinsic absorption With the higher columndensity in the Galaxy such partially visible SSS may not besufficiently luminous for detection this is an important factorto take into account when constraining nova parameters onthe basis of the SSS detection duration and behavior

10 CONCLUSIONS

Our exploration of the N LMC 2009a X-ray high resolutionspectra has highlighted their complexity and the likely su-perposition of different regions of emission We also searchedthe X-ray archives and discovered four more supersoft X-ray

20 M Orio et al

Table 7 Pointed and serendipitous observations of MC novae in outburst satellite used time after outburst in days (d) months (m) or

years (yr) number of exposures X-ray detection (yes or no) whether the nova was a RN and publications The novae are identified byyear and month of outburst and the names of the (only) serendipitously observed ones are in boldface The whole row is in boldface if

there was a detection

Name Satellite pointed when how many X-ray on RN reference

LMC 2020-07 Swift yes 3d-6m 80 yes 1968 1990 Page et al (2020)20162020

2016 outb Swift yes 7d-11m 80 yes Kuin et al (2020)

SMC 2019-7 Swift yes 10d-4m 5 yes(4m)LMC 2018-5 eRosita survey 21m several yes Ducci et al (2020)

Swift yes 22m-25m 16 yes

LMC 2018-02 Swift yes 9d-5m 50 yes yes 1996 Page et al (2018)LMC 2017-11 Swift yes 14d-1yr 46 no Bahramian et al (2018)

SMC 2016-10 Swift yes 6d-1yr 111 yes perhaps Orio et al (2018)

XMM-Newton yes 1 75d rdquoChandra yes 2 39d88d rdquo

LMC 2016-04 Swift yes 14d-48d 29 yes probably

LMC 2015-03 Swift yes few days 3 noLMC 2012-11 Swift yes 1d 1 no

LMC 2012-10 Swift yes 7d 1 noSMC 2012-09 Swift no gt13m several no

Chandra no 214m 2

SMC 2012-03 Swift yes 4m-14m 85 yes Schwarz et al (2012)Page et al (2013ab)

LMC 2012-03 Swift yes 1d-21 m 72 yes Schwarz et al (2015)

Chandra yes yes rdquoSMC 2011-11 Maxi no 0d 1 yes Li et al (2012) Morii et al (2013)

Swift yes yes

LMC 2011-08 Swift no 1yr 1 noLMC 2009-05 Swift yes 3yr 4 no

LMC 2009-02 Swift yes 9d-1yr 82 yes perhaps Bode et al (2016)

XMM-Newton yes 90-229d 4 yes this paperSMC 2008-10 XMM-Newton no 1yr 1 yes

Swift no 4-10yr several noSMC 2006-08 XMM-Newton no gt3yr 3 no

LMC 2005-11 Swift yes 1m 3y 4y 7 no

XMM-Newton no 5yr7yr 7 noSwift no gt7yr several no

LMC 2005-09 XMM-Newton no 21m 1 yes

Swift XMM no 3-13yr several noSMC 2005-08 XMM-Newton y 6m 1 no

Swift no 1yr-11yr 7 noXMM-Newton no 4yr-11yr 8 no

LMC 2004-10 XMM-Newton no 21yr 39yr 1 yesSMC 2004-06 XMM-Newton no 525yr 1 yes

LMC 2003-06 XMM-Newton no gt10yr 4 noSMC 2002-10 XMM-Newton no 10yr 15yr 2 no

SMC 2001-10 XMM-Newton no 45yr 6yr 8yr 3 noLMC 2001-08 Swift no 5-10yr several no

XMM-Newton no 11yr16yr 2 no

sources albeit at lower luminosity than expected These areour main conclusions

bull The continuum of the spectra of N LMC 2009 indicatesthe supersoft emission of the atmosphere of a WD with effec-tive temperature peaking above 810000 K (the PION black-body source) and likely to be around a million K (the TMAPmodel result) corresponding to a WD in the 12-14 Mrange The continuum and its absorption edges can be wellreproduced only assuming low oxygen abundance in the inter-vening interstellar medium and above all enhanced nitrogen

by a factor around 100 times solar in the nova atmosphereandor residual wind near the surface where we assume thatthe absorption features originate

bull The blueshift of the absorption features is explained bya mass outflow rate of the order of 10minus8 M yrminus1 Novamodels usually assume that mass loss has ceased when theSSS emerges but like in other novae this does not appear tobe true some residual mass loss is still occurring

bull The absorption features in this nova were never as deep(or even saturated) as in other novae bserved in the Galaxy

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

Figure 14 TMAP atmospheric fit to the spectra of Novae SMC 2008-10 LMC 2005-11 LMC 2004-10 SMC 20046 at 1 18 39 and 525years post-outburst respectively

Table 8 Count rates and spectral fits with TMAP to the XMM-Newton observations of MC novae For the best fit we assumed a minimumN(H) of 35 times1020 cmminus2

Nova Date counts sminus1 N(H) times1020 cmminus2 Teff (K) Lx times 1035 erg sminus1

LMC 2004-10 2006-12-2 00145plusmn00033 35+13minus35 476000plusmn148 000 035+114

minus034

2008-09-03 00218plusmn00028 35+16minus35 671000plusmn112 000 031+056

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

and in the Clouds as the comparison with KT Eri and withN SMC 2016 shows clearly While the peak temperature in NLMC 2009 may have been 100000-200000 K hotter imply-ing a higher ionization parameter the difference is so largethat it is likely to have been due also to different abundancesand density in the medium in which the absorption featuresoriginated

bull The ejecta of this nova emitted additional thermal X-rayflux that produced a complex emission line spectrum most

likely arising from multiple regions at different temperatureswith a contribution of both photoionization and shock ion-ization

bull Nova KT Eri seems to have a high mass WD and a par-tially evolved companion in common with N LMC 2009 How-ever in N LMC 2009 the turn-on time was longer and theduration of the SSS was comparable so the ejecta initiallyabsorbing the SSS emission may have had higher mass butthe left-over envelope was of the same order of magnitude

22 M Orio et al

Since N LMC 2009a is a RN with an inter-outburst period ofonly 38 years while no outburst of KT Eri have been foundin tens of years before the eruption N LMC 2009 did nothave the time to accrete comparable or higher mass beforethe outburst unless it had high m which in turn would haveresulted in ejection after accretion of a small mass unless theWD before the outburst was still relatively cool (see Yaronet al 2005) Most likely this nova is at only the beginning ofits RN cycle with short inter-outburst periods and the WDsurface has not been heated yet by a repeated outburst cycle(see Yaron et al 2005)

bull The 33s pulsation varied in amplitude and in length of theperiod over time scales of hours The search for the physicalroot cause of this intriguing phenomenon already observedalso in other novae must take this fact into account

bull N LMC 2009 was an order of magnitude less intrinsicallyluminous than the level compatible with emission arising fromthe whole surface The predicted flux level was not observedin all SSS-novae but it was indeed measured in N SMC 2016as well as in other novae (eg RS Oph Nelson et al 2008)On the other hand the portion of expected WD flux that isobserved is much larger than in U Sco in which only Thomsonscattered radiation was detected We suggested that in NLMC 2009a we observed the WD directly along the line ofsight but either dense remaining clumps in the ejecta or anon-disrupted accretion disk blocked the whole of the wholeWD atmosphere The clumps are a more likely explanationbecause of the variability in the continuum level indicatingvarying visibility The scenario we suggest is one in which partof the material in an outflow in which instabilities occurredwas still opaque to X-rays

bull We discovered that four other MC novae were serendip-itously observed as SSS with low column density There wasno indication of flux variation and the absolute SSS luminos-ity was only about a factor of a thousand less than predicted(and indeed observed in the most luminous SSS-novae) Wehypothesize that partial obscuration of the SSS was due toan accretion disk at high inclination since these novae weredetected long after the end of mass loss and it is unlikely thatthe ejecta still obscured the WD

bull The statistics of the MC novae of the last 20 years indi-cates that novae that are still SSS after 6 or more years fromthe outburst are rare We also found that half of all novaewere detected as SSS for at least several months between fewdays and 55 years after the outburst Since the sampling wasdone mostly at sparse post-outburst times and it never lastedfor more than a few months with Swift or covered only oneor two random epochs with XMM-Newton the percentageof novae detectable as SSS within 6 years from the outburstwould actually be quite higher if an uninterrupted survey waspossible

DATA AVAILABILITY

The data analyzed in this article are all available in theHEASARC archive of NASA at the following URL httpsheasarcgsfcnasagovdb-perlW3Browsew3browsepl

ACKNOWLEDGEMENTS

M Orio was supported by a NASA grant for XMM-Newtondata analysis AD was supported by the Slovak grant VEGA1040820 and by the Operational Programme Research andInnovation for the project ldquoScientific and Research Centre ofExcellence SlovakION for Material and Interdisciplinary Re-searchrdquo project code ITMS2014+313011W085 co-financedby the European Regional Development Fund

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Aydi E et al 2018a MNRAS 474 2679

Aydi E et al 2018b MNRAS 480 572Aydi E et al 2019 arXiv e-prints p arXiv190309232

Aydi E et al 2020 ApJ 905 62

Bahramian A Chomiuk L Strader J Kuin P Darnley M JPage K 2018 The Astronomerrsquos Telegram 11301 1

Beardmore A P et al 2010 The Astronomerrsquos Telegram 2423

1Beardmore A P et al 2012 AampA 545 A116

Bode M F et al 2016 ApJ 818 145

Bond H E Walter F M Cosgrove E Espinoza J Liller W2009 IAU Circ 9019

Cash W 1979 ApJ 228 939

Dobrotka A Ness J-U 2017 MNRAS 467 4865Dorman B Arnaud K A 2001 in Harnden F R J Primini

F A Payne H E eds Astronomical Society of the PacificConference Series Vol 238 Astronomical Data Analysis Soft-

ware and Systems X p 415

Drake J J et al 2003 ApJ 584 448Ducci L et al 2020 The Astronomerrsquos Telegram 13545 1

Finzell T Chomiuk L Munari U Walter F M 2015 ApJ 809

160Heise J van Teeseling A Kahabka P 1994 AampA 288 L45

Jose J Hernanz M Iliadis C 2006 Nuclear Phys A 777 550

Kaastra J S 2017 AampA 605 A51Kaastra J S Mewe R Nieuwenhuijzen H 1996 in UV and X-

ray Spectroscopy of Astrophysical and Laboratory Plasmas pp

411ndash414Kuin N P M et al 2020 MNRAS 491 655

Li K L et al 2012 Apj 761 99Liller W 2009 IAU Circ 9019

Mehdipour M Kaastra J S Kallman T 2016 AampA 596 A65Morii M et al 2013 Apj 779 118Mroz P et al 2016 ApJS 222 9

Nelson T Orio M Cassinelli J P Still M Leibowitz E Muc-

ciarelli P 2008 ApJ 673 1067Ness J U Starrfield S Jordan C Krautter J Schmitt

J H M M 2005 MNRAS 364 1015Ness J U Drake J J Starrfield S Bode M Page K Beard-

more A Osborne J P Schwarz G 2010 The Astronomerrsquos

Telegram 2418 1

Ness J U et al 2011 Apj 733 70Ness J-U et al 2012 ApJ 745 43

Ness J U et al 2013 AampA 559 A50Ness J U et al 2015 AampA 578 A39

Odendaal A Meintjes P J 2017 MNRAS 467 2797

Odendaal A Meintjes P J Charles P A Rajoelimanana A F2014 MNRAS 437 2948

Orio M 2012 Bulletin of the Astronomical Society of India 40

333Orio M Covington J Ogelman H 2001 AampA 373 542

Orio M Hartmann W Still M Greiner J 2003a The Astro-

physical Journal 594 435Orio M Hartmann W Still M Greiner J 2003b The Astro-

physical Journal 594 435

Orio M Mason E Gallagher J Abbott T 2009 The As-

tronomerrsquos Telegram 1930

Orio M Behar E Gallagher J Bianchini A Chiosi E Luna J

Nelson T Rauch T 2013a in Di Stefano R Orio M Moe Meds Vol 281 Binary Paths to Type Ia Supernovae Explosions

pp 181ndash185 doi101017S1743921312014950

Orio M et al 2013b MNRAS 429 1342

Orio M Henze M Ness J 2017 in Ness J-U Migliari S eds

The X-ray Universe 2017 p 165

Orio M et al 2018 ApJ 862 164

Page K L Walter F M Schwarz G J Osborne J P 2013a

The Astronomerrsquos Telegram 4853 1

Page K L Osborne J P Beardmore A P Schwarz G J 2013bThe Astronomerrsquos Telegram 4920 1

Page K L Kuin N P M Henze M 2018 The Astronomerrsquos

Telegram 11410 1

Page K L Beardmore A P Osborne J P 2020 Advances in

Space Research 66 1169

Pagnotta A et al 2015 ApJ 811 32

Payne-Gaposchkin C H 1964 The galactic novae

Peretz U Orio M Behar E Bianchini A Gallagher J Rauch

T Tofflemire B Zemko P 2016 ApJ 829 2

Pietrzynski G et al 2019 Nature 567 200

Pinto C Ness J U Verbunt F Kaastra J S Costantini E

Detmers R G 2012 AampA 543 A134

Prialnik D 1986 Apj 310 222

Rauch T Orio M Gonzales-Riestra R Nelson T Still MWerner K Wilms J 2010 ApJ 717 363

Rohrbach J G Ness J U Starrfield S 2009 AJ 137 4627

Scargle J D 1982 ApJ 263 835

Schaefer B E et al 2010 AJ 140 925

Schwarz G J et al 2011 ApJS 197 31

Schwarz G J Osborne J P Page K Walter F M Starrfield S2012 The Astronomerrsquos Telegram 4501 1

Schwarz G J et al 2015 Apj 149 95

Smith R K Brickhouse N S Liedahl D A Raymond J C2001 ApJ 556 L91

Starrfield S Timmes F X Iliadis C Hix W R Arnett W D

Meakin C Sparks W M 2012 Baltic Astronomy 21 76

Strope R J Schaefer B E Henden A A 2010 AJ 140 34

Tofflemire B M Orio M Page K L Osborne J P Ciroi S

Cracco V Di Mille F Maxwell M 2013 ApJ 779 22

Trudolyubov S P Priedhorsky W C 2008 ApJ 676 1218

Williams R E 1992 AJ 104 725

Wilms J Allen A McCray R 2000 ApJ 542 914

Wolf W M Bildsten L Brooks J Paxton B 2013 ApJ 777

Wolf W M Townsend R H D Bildsten L 2018 ApJ 855 127

Yaron O Prialnik D Shara M M Kovetz A 2005 AJ 623 398

den Herder J W et al 2001 AampA 365 L7

van Rossum D R 2012 Apj 756 43

This paper has been typeset from a TEXLATEX file prepared bythe author

APPENDIX A SIMULATIONS OF THE AUGUST 2009LIGHT CURVE

We based this simulation on the August pn data because theyyielded the highest count rate and the most complex features We

first fitted the pn data with a polynomial (25th order P25) in

order to model the long-term trend and on P25 we added a si-nusoidal function and Gaussian noise G The latter represents the

residual scatter of flux after subtracting P25 from the observed

Table A1 Sine parameters of the simulated signal amplitude (a)

and periodicity (p) da and dp represent the rate of variability of

the corresponding parameter (see text for details) No da or nodp values means (constant) Pa = a or Pp = p in equation (A2)

respectively

model p dp a da best χ2red

(s) (s) (ctss) (ctss)

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

data 2 The flux ψ thus can be expressed with this equation

ψ = P25 + a sin(2π tp) + G (A1)

We performed simulations with constant and with variable peri-odicity p and amplitude a Table A1 summarizes the parameters p

and a For the variable periodicity simulations we needed a smooth

function describing the variability of amplitude orand periodicityso we generated random points over the time interval of the expo-

sure3 with a Gaussian distribution in which p and a are the mean

values and dp and da are the corresponding variances We fittedthese points with a polynomial (Pa or Pp) the required smooth

function used as input for the sine function

ψ = P25 + Pa sin(2π tPp) + G (A2)

If the amplitude drops at or below zero the modulation is consid-

ered to be absent (a = 0) As input values for the mean periodicityp we used the most significant periodicities P1 P2 and P3 from

Table 6 and we varied the amplitude until we obtained the best

match For every model we run 10000 simulations and calculatedthe periodogram using a Fast Fourier transform (it allows a much

faster calculation than the Lomb-Scargle method) We selected abest case using the sum of the residual squares Σ(ominuss)2 calculated

over a given frequency interval where o and s are the observed and

simulated powers at a given periodicity in the periodogram Thegray shaded area in the main panels of Figs A1 and A2 shows the

frequency interval we used The sums of residual squares are rela-

tive numbers and the minimum indicates the best value Howeverit is important to evaluate also the real goodness of the model

χ2red =

(ominus s)2

σ2 (A3)

where N is the number of degrees of freedom (number of peri-

odogram points over which the χ2red is calculated) In order to

estimate σ we assumed that the periodogram outside the main

pattern (marked as darker shaded area in Figs A1 and A2) con-

tains random features attributed to noise We assumed that thenoise power is exponentially distributed and as σ we chose thepower at the 90 level in the cumulative histogram (527) exclud-

ing one relatively significant peak at 312 s which is of unknownorigin Fig A1 shows the comparison of the observed periodogram

with the best simulated one with variable amplitude and period

In the upper panel we show a case in which both parameters are

2 It yields a very similar flux distribution to the simple Poissonnoise3 Also a short time before and after the exposure to avoid bound-

ary fitting effects and using a step of 200 s

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

Figure A1 Comparison of the observed data in August and the

best of 10000 simulated periodograms for models B and F as in

Table A1 The insets show the evolution of the simulated ampli-tude (in count rate) and periodicity The light shaded area is the

frequency interval over which the χ2red is calculated The darker

area represents the interval over which we calculated the poweruncertainty σ (equal to the vertical extent of the shaded area)

variable and in the lower panel a case with constant amplitude and

variable period The best case is model B in which both parame-ters are variable The simulated periodogram describes almost all

the observed features supporting the interpretation that the sig-

nal is variable and the periodicity oscillates around P2 The periodvariability is depicted in the lower inset Model F with constant

amplitude and variable period also reproduces all the observed

features but the amplitudes are significantly different and the pe-riodicity oscillates around P3 matching the dominant peaks in all

the observed light curves except the non pile-up-corrected August

pn light curve We remind that Dobrotka amp Ness (2017) explainedthe double peak periodogram feature in V4743 Sgr as a false beat

in the observed data Two close periodicities result in a beat withlow frequency but if a single signal changes its amplitude or disap-

pears for some time this effect mimics a beat so and the numerical

method rdquointerpretsrdquo it as due to two close frequencies The sameprinciple can explain the non-single peak in V2491 Cyg (Ness et al

Fig A2 shows the best case with constant periodicity but vari-able amplitude However a was set to zero yielding the amplitudeoscillate around zero and disappearing more frequently mimick-ing a false beat Larger values of a yield only a single dominant

peak which do not describe the observed feature at all The bestcase reproduces all the observed features with χ2

red even better

than model F Models G and I yield single peak solutions and donot describe the complex observed pattern Model H is acceptableand it supports a constant periodicity P2 with variable amplitudeHowever model B describes the observed periodogram much bet-ter and indicates a variable signal With model H we were not able

to retrieve the observed power configuration ie P2 having lowerpower than P1 and P3

4 Any periodicity introduced in the modelproduces the highest or a very significant peak at the given period

while the models with variable periodicity are more flexible and

4 We repeated the 10000 simulation process several times

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

Figure A2 The same as Fig A1 but for model H

appear to be more realistic We note here that interesting period-

icity evolution is shown in the upper inset of Fig A1 Althoughthe figure shows only a solution out of many possible ones and an

exact match is not expected the significant decrease of the period

length towards the end of the exposure is in agreement with theperiodogram of the third time interval obtained when we split the

exposure in three portions (see text)

1 Introduction

11 Nova LMC 2009A

2 The Observations

3 Irregular variability and spectral variability

4 Identifying the spectral features

5 Spectral evolution and the viable spectral models

6 Comparison with the spectra of other novae

7 Timing analysis revisiting the 33 s period

71 Periodograms


8 Discussion N LMC 2009a

9 Archival X-ray exposures of other novae in the Magellanic Clouds

10 Conclusions

A Simulations of the August 2009 light curve

2 M Orio et al

05067 UT by Liller (2009) and spectroscopically confirmedby Bond et al (2009) It was later identified as a RN co-inciding with N LMC 1971b (Bode et al 2016) RN are theones recurring on human time scales although the models in-dicate that all outburst recur (ie Prialnik 1986) An opticalspectrum obtained in outburst by Orio et al (2009) showedprominent emission lines of H He and N so this nova is aHeN one in the classification scheme of Williams (1992) likethe other RNe we know Orio et al (2009) reported a largeexpansion velocity with the full width at half maximum ofthe Hα line slightly above 4200 km sminus1 Additional spectraobtained by Bode et al (2016) showed expansion velocitiesderived from different lines and at different phases between1000 and 4000 km sminus1 Coronal line emission before day 9indicated shocks in the ejecta The initial decay was fast andthe time t3 for a decay by 3 magnitudes lasted from 104days in the V band to 227 days in the infrared K The timet2 for a decay by 2 magnitudes ranged from 5 days (V filter)to 128 days (K filter) These parameters are pertinent to aclassification as a ldquovery fastrdquo nova (Payne-Gaposchkin 1964)

By comparison with the grid of nova models by Yaronet al (2005) the characteristic parameters of the outburst(recurrence time of 38 years velocity reaching 4000 km sminus1t3=114 days in the V band amplitude of about 9 mag in V)place the nova the highest WD mass range (14 M) with arather young and hot WD at the start of accretion and massaccretion rate m of a few 10minus8 M However the models in-clude only a constant mass accretion rate m which may notbe the case in some novae and probably not for RN whoserecurrence time has been observed to vary (while the envelopemass accreted to trigger the burning outburst is expected toremain the same)

Bode et al (2016) identified the progenitor system theoptical and infrared magnitude in different filters and thecolour indexes are best interpreted with the presence of a sub-giant feeding a luminous accretion disk Modulations with aperiod P=12 days most probably orbital in nature wereevident in the UV and optical flux since day 43 (Bode et al2016) Two other RNe with orbital periods of the order of aday and sub-giant evolved secondaries are the Galactic novaeU Sco and V394 CrA There is also evidence that also a thirdRN V2487 Oph hosts a sub-giant although its orbital periodhas not been measured yet (Strope et al 2010) Other novasystems with suspected subgiant secondaries and day-longorbital periods are KT Eri (also a candidate RN but so farwithout previous known outbursts Bode et al 2016) HV Cet(Beardmore et al 2012) and V1324 Sco (Finzell et al 2015)

Luminous CNe and RNe are monitored regularly with Swiftin UV and X-rays It is known that all nova shells emit X-raysin outburst (eg Orio 2012) although they are not usuallyluminous enough to be detected at LMC distance Howeverwhen the ejecta become optically thin to soft X-rays thephotosphere of the WD contracts and shrinks to close to pre-outburst dimension (Starrfield et al 2012 Wolf et al 2013)while CNO burning still occurs close to the surface with onlya thin atmosphere on top for a period of time ranging fromdays to years (Orio et al 2001 Schwarz et al 2011 Page et al2020) Because the WD effective temperature Teff is in the150000 K to a million K range the WD atmosphere peaks inthe X-ray range or very close to it and the WD detected asa luminous supersoft X-ray source (SSS) observable at thedistance of the Clouds also thanks to the low column density

Strengthening of the He II 4686A line in the N LMC 2009aspectrum preceded the emergence of the central WD as asupersoft X-ray source (hereafter SSS) observed in X-rayswith the Swift X-Ray Telescope (XRT) since day 63 TheSSS initially was at lower luminosity but became much moreluminous around day 140 The following X-ray observationsindicated an approximate constant average luminosity (al-beit with large fluctuations from day to day) until aroundday 240 of the outburst The SSS was always variable peri-odically and aperiodically and clear oscillations with the 12days period were observed (Bode et al 2016) with a delay of028P with respect to the optical modulations

Not all novae are sufficiently X-ray luminous to be studiedwith the gratings in detail especially if they are as far as theMagellanic Clouds and we did not want to miss the occasionof the X-ray luminous Nova LMC 2009 so in addition to SwiftX-Ray Telescope (XRT) (Bode et al 2016) XMM-Newtonwas used for longer exposures and high spectral resolution

2 THE OBSERVATIONS

The rise observed with the Swift XRT prompted two obser-vations in the Director Discretionary Time (DDT) requestedby W Pietsch 90 and 165 days after the optical maximumobserved on 2009 February 6 (Liller 2009) In July of 2009the nova was sufficiently X-ray bright to trigger also two pre-approved target of Opportunity (TOO) observations awardedto PI M Orio These exposures were done respectively days197 and 229 after the optical discovery at the observed opti-cal maximum All four XMM-Newton observations are listedin Table 1 While partial results were presented in Orio et al(2013a 2017) this paper contains the first comprehensiveanalysis of all the data

The XMM-Newton observatory consists of five different in-struments behind three X-ray mirrors plus an optical mon-itor (OM) and all observe simultaneously For this paperwe used the spectra from the Reflection Grating Spectrom-eters (RGS den Herder et al 2001) and the light curves ofthe EPIC pn and MOS cameras The calibrated energy rangeof the EPIC cameras is 015-12 keV for the pn and 03-12keV for the MOS The RGS wavelength range is 6-38 A cor-responding to the 033-21 keV energy range Table 1 showsthat in the first two observations the EPIC cameras were usedin imaging mode the pn detector was ldquosmall window moderdquoto mitigate pile up and the medium filter was used while theMOS was used with the ldquosmallrdquo frame and the medium filterThe set up of the third and fourth observation was the samewith larger MOS2 window size and with the thin (instead ofthe medium) filter for both MOS

The EPIC pn and MOS detectors were used to ex-tract light curves with the XMMSAS (XMM Science Anal-ysis System) task XMMSELECT after applying barycen-tric corrections to the event files choosing only single-photon events (PATTERN=0) in the eventsrsquo files A refer-ence for this and the other XMMSAS tasks mentioned be-low is httpsxmm-toolscosmosesaintexternalxmm_

user_supportdocumentationsas_usgUSGpdf The re-sulting source light curves were corrected for background vari-ations using the XMMSAS task epiclccorr Because therewas essentially no emission above 08 keV we used only theRGS with their high spectral resolution for the spectral anal-

15 20 25 30 35

(ks) (UT) (d)

Liller 2009)

4 M Orio et al

(see text)

6 M Orio et al

2460 2465 2470 2475 2480 2485 2490 2495 2500Wavelength ( )

1000 0 1000 2000 3000(km s 1)

best fit

2750 2755 2760 2765 2770 2775Wavelength ( )

Ar XIV

1500 1000 500 0 500 1000(km s 1)

Ar XIV

best fit

291 292 293 294 295 296Wavelength ( )

Ar XIII

3000 2000 1000 0 1000(km s 1)

Ar XIII

best fit

3020 3025 3030 3035 3040 3045 3050 3055 3060Wavelength ( )

3000 2000 1000 0 1000 2000(km s 1)

best fit

3200 3205 3210 3215 3220 3225 3230 3235 3240Wavelength ( )

S XIII

2000 1500 1000 500 0 500 1000 1500(km s 1)

S XIII

best fit

8 M Orio et al

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

minus3

2times10

minus3

3times10

minus3

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

10 M Orio et al

0610000501

0604590301

0604590401

minus19 3

minus004 949+020minus017 558+016

minus008

kT1 (eV) 50+8minus0 55+2

minus002 583+1100minus250 017+026

minus016

00 (ISM) 006 ()

NN 100minus7 ()

00 13plusmn2

ξ (2) 302 erg cm

nH = (ξL)(NHfcβ)2

12 M Orio et al

gdr2_distancespdf

14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


15 20 25 30 35

(ks) (UT) (d)

Liller 2009)

4 M Orio et al

(see text)

6 M Orio et al

2460 2465 2470 2475 2480 2485 2490 2495 2500Wavelength ( )

1000 0 1000 2000 3000(km s 1)

best fit

2750 2755 2760 2765 2770 2775Wavelength ( )

Ar XIV

1500 1000 500 0 500 1000(km s 1)

Ar XIV

best fit

291 292 293 294 295 296Wavelength ( )

Ar XIII

3000 2000 1000 0 1000(km s 1)

Ar XIII

best fit

3020 3025 3030 3035 3040 3045 3050 3055 3060Wavelength ( )

3000 2000 1000 0 1000 2000(km s 1)

best fit

3200 3205 3210 3215 3220 3225 3230 3235 3240Wavelength ( )

S XIII

2000 1500 1000 500 0 500 1000 1500(km s 1)

S XIII

best fit

8 M Orio et al

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

minus3

2times10

minus3

3times10

minus3

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

10 M Orio et al

0610000501

0604590301

0604590401

minus19 3

minus004 949+020minus017 558+016

minus008

kT1 (eV) 50+8minus0 55+2

minus002 583+1100minus250 017+026

minus016

00 (ISM) 006 ()

NN 100minus7 ()

00 13plusmn2

ξ (2) 302 erg cm

nH = (ξL)(NHfcβ)2

12 M Orio et al

gdr2_distancespdf

14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


4 M Orio et al

(see text)

6 M Orio et al

2460 2465 2470 2475 2480 2485 2490 2495 2500Wavelength ( )

1000 0 1000 2000 3000(km s 1)

best fit

2750 2755 2760 2765 2770 2775Wavelength ( )

Ar XIV

1500 1000 500 0 500 1000(km s 1)

Ar XIV

best fit

291 292 293 294 295 296Wavelength ( )

Ar XIII

3000 2000 1000 0 1000(km s 1)

Ar XIII

best fit

3020 3025 3030 3035 3040 3045 3050 3055 3060Wavelength ( )

3000 2000 1000 0 1000 2000(km s 1)

best fit

3200 3205 3210 3215 3220 3225 3230 3235 3240Wavelength ( )

S XIII

2000 1500 1000 500 0 500 1000 1500(km s 1)

S XIII

best fit

8 M Orio et al

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

minus3

2times10

minus3

3times10

minus3

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

10 M Orio et al

0610000501

0604590301

0604590401

minus19 3

minus004 949+020minus017 558+016

minus008

kT1 (eV) 50+8minus0 55+2

minus002 583+1100minus250 017+026

minus016

00 (ISM) 006 ()

NN 100minus7 ()

00 13plusmn2

ξ (2) 302 erg cm

nH = (ξL)(NHfcβ)2

12 M Orio et al

gdr2_distancespdf

14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


(see text)

6 M Orio et al

2460 2465 2470 2475 2480 2485 2490 2495 2500Wavelength ( )

1000 0 1000 2000 3000(km s 1)

best fit

2750 2755 2760 2765 2770 2775Wavelength ( )

Ar XIV

1500 1000 500 0 500 1000(km s 1)

Ar XIV

best fit

291 292 293 294 295 296Wavelength ( )

Ar XIII

3000 2000 1000 0 1000(km s 1)

Ar XIII

best fit

3020 3025 3030 3035 3040 3045 3050 3055 3060Wavelength ( )

3000 2000 1000 0 1000 2000(km s 1)

best fit

3200 3205 3210 3215 3220 3225 3230 3235 3240Wavelength ( )

S XIII

2000 1500 1000 500 0 500 1000 1500(km s 1)

S XIII

best fit

8 M Orio et al

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

minus3

2times10

minus3

3times10

minus3

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

10 M Orio et al

0610000501

0604590301

0604590401

minus19 3

minus004 949+020minus017 558+016

minus008

kT1 (eV) 50+8minus0 55+2

minus002 583+1100minus250 017+026

minus016

00 (ISM) 006 ()

NN 100minus7 ()

00 13plusmn2

ξ (2) 302 erg cm

nH = (ξL)(NHfcβ)2

12 M Orio et al

gdr2_distancespdf

14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


6 M Orio et al

2460 2465 2470 2475 2480 2485 2490 2495 2500Wavelength ( )

1000 0 1000 2000 3000(km s 1)

best fit

2750 2755 2760 2765 2770 2775Wavelength ( )

Ar XIV

1500 1000 500 0 500 1000(km s 1)

Ar XIV

best fit

291 292 293 294 295 296Wavelength ( )

Ar XIII

3000 2000 1000 0 1000(km s 1)

Ar XIII

best fit

3020 3025 3030 3035 3040 3045 3050 3055 3060Wavelength ( )

3000 2000 1000 0 1000 2000(km s 1)

best fit

3200 3205 3210 3215 3220 3225 3230 3235 3240Wavelength ( )

S XIII

2000 1500 1000 500 0 500 1000 1500(km s 1)

S XIII

best fit

8 M Orio et al

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

minus3

2times10

minus3

3times10

minus3

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

10 M Orio et al

0610000501

0604590301

0604590401

minus19 3

minus004 949+020minus017 558+016

minus008

kT1 (eV) 50+8minus0 55+2

minus002 583+1100minus250 017+026

minus016

00 (ISM) 006 ()

NN 100minus7 ()

00 13plusmn2

ξ (2) 302 erg cm

nH = (ξL)(NHfcβ)2

12 M Orio et al

gdr2_distancespdf

14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


8 M Orio et al

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

minus3

2times10

minus3

3times10

minus3

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

10 M Orio et al

0610000501

0604590301

0604590401

minus19 3

minus004 949+020minus017 558+016

minus008

kT1 (eV) 50+8minus0 55+2

minus002 583+1100minus250 017+026

minus016

00 (ISM) 006 ()

NN 100minus7 ()

00 13plusmn2

ξ (2) 302 erg cm

nH = (ξL)(NHfcβ)2

12 M Orio et al

gdr2_distancespdf

14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


8 M Orio et al

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

minus3

2times10

minus3

3times10

minus3

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

10 M Orio et al

0610000501

0604590301

0604590401

minus19 3

minus004 949+020minus017 558+016

minus008

kT1 (eV) 50+8minus0 55+2

minus002 583+1100minus250 017+026

minus016

00 (ISM) 006 ()

NN 100minus7 ()

00 13plusmn2

ξ (2) 302 erg cm

nH = (ξL)(NHfcβ)2

12 M Orio et al

gdr2_distancespdf

14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


20 25 30 35

minus3

2times10

minus3

3times10

minus3

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

20 25 30 35

02times

10minus

34times

10minus

36times

10minus

38times

10minus

s sminus

1 Aringminus

minus2

Wavelength (Aring)

10 M Orio et al

0610000501

0604590301

0604590401

minus19 3

minus004 949+020minus017 558+016

minus008

kT1 (eV) 50+8minus0 55+2

minus002 583+1100minus250 017+026

minus016

00 (ISM) 006 ()

NN 100minus7 ()

00 13plusmn2

ξ (2) 302 erg cm

nH = (ξL)(NHfcβ)2

12 M Orio et al

gdr2_distancespdf

14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


10 M Orio et al

0610000501

0604590301

0604590401

minus19 3

minus004 949+020minus017 558+016

minus008

kT1 (eV) 50+8minus0 55+2

minus002 583+1100minus250 017+026

minus016

00 (ISM) 006 ()

NN 100minus7 ()

00 13plusmn2

ξ (2) 302 erg cm

nH = (ξL)(NHfcβ)2

12 M Orio et al

gdr2_distancespdf

14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


minus19 3

minus004 949+020minus017 558+016

minus008

kT1 (eV) 50+8minus0 55+2

minus002 583+1100minus250 017+026

minus016

00 (ISM) 006 ()

NN 100minus7 ()

00 13plusmn2

ξ (2) 302 erg cm

nH = (ξL)(NHfcβ)2

12 M Orio et al

gdr2_distancespdf

14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


12 M Orio et al

gdr2_distancespdf

14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


gdr2_distancespdf

14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


14 M Orio et al

16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


16 M Orio et al

at rest wavelength)

71 Periodograms

18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


18 M Orio et al

30 31 32 33 34 35 36

August (day 197)

period [s]

PNPN no central

18August (day 197)

PNMOS1

18July (day 165)

PN MayPN Sep

15 20 25 30 35 40 45 50

15 20 25 30 35 40 45

332 333 334 335

327 330 333 336

in red

32 325 33 335 34

period [s]

2 third3 third

r 1 third2 third

20P1 P2 P3

r 1 half2 half

10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


10 CONCLUSIONS

20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


20 M Orio et al

Chandra no 214m 2

Swift yes yes

s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


s sminus

Vminus

Energy (keV)

Nova SMC 2008

102 05

s sminus

Vminus

Energy (keV)

N LMC 2005minus09

102 05

s sminus

Vminus

Energy (keV)

N LMC 2004minus10

102 05

s sminus

Vminus

Energy (keV)

Nova SMC 2004

minus034

minus023

SMC 2004-06 2009-09-13 00073plusmn00007 88+89minus56 404000+49000

minus88000 470+530minus469

LMC 2005-09 2007-06-19 01645plusmn00066 42+22minus18 715000+24000

minus15000 240+172minus118

SMC 2008-10 2009-09-27 00081plusmn00009 35+11minus35 520000+165000

minus50000 197+31000minus187

22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


22 M Orio et al

DATA AVAILABILITY

ACKNOWLEDGEMENTS

REFERENCES

Cash W 1979 ApJ 228 939

Telegram 2418 1

pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


pp 181ndash185 doi101017S1743921312014950

Telegram 11410 1

respectively

A 329 05 10 25 187B 331 05 10 25 111

C 333 05 10 25 199

D 329 05 10 ndash 202E 331 05 10 ndash 174

F 333 05 10 ndash 152

G 329 ndash 00 25 186H 331 ndash 00 25 146

I 333 ndash 00 25 193

ψ = P25 + a sin(2π tp) + G (A1)

ψ = P25 + Pa sin(2π tPp) + G (A2)

χ2red =

(ominus s)2

σ2 (A3)

24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


24 M Orio et al

30 31 32 33 34 35 36

period [s]

PNmodel F χ

2red = 152

PNmodel B χ

2red = 111

0 10 20 30

time [ks]

0 10 20 30

time [ks]

200ctr

red even better

30 31 32 33 34 35 36

period [s]

PNmodel H χ

2red = 146

0 5 10 15 20 25 30

time [ks]

1 Introduction

11 Nova LMC 2009A

2 The Observations






71 Periodograms




10 Conclusions


Documents

Nova LMC 2009a as observed with XMM-Newton, compared with