Asteroseismology from Line-profile variations

PaulBeck

JuandelaCiervaFellowSismologia SolaryEstelaryBusquedadeExoplanetas (SSEBE)

InstitutodeAstrofisica deCanarias,Tenerife,Spain.

1@BeckPaulG

A strategic partnership between Intituto de Astrofisica de Canarias (IAC) and various Czech and Slovak institutes

Opportunities:• Students/postdocs spend ~6 months at the IAC/GTC• Short-term stays at IAC for more senior staff• Schools on modern astronomical

instrumentation/observations• Host researchers from the IAC

IACheadquarters, LaLaguna, TenerifeIACCALP,LaPalma

TeideObservatory,TenerifeRoquedelos Muchachos Obs.,LaPalma

Sales pitch:“Stellar Noise”Asteroseismology isauniquetooltoaccuratelycharacterizeaplanet-host star

Knowthystar– knowthyplanet

98%ofallexoplanetdetectionsconstraintheplanetarypropertiesrelativetothestaràmass,radius,logg <5%,age<10%

Uncertainty:

stellarparameters<>planetarydensity<>planetarystructure

SummaryofTalk

• BasicsofobservationalAsteroseismology• Line-profile variationsandmodeID• Examplesofcampaigns

usingspectroscopyforseismology

Temperature and Velocity Variations

l =totalnumberofnodallinesonsurface

m=nodallines,perpendiculartoequator(m≤l)

l =0

l =1

l =2

l =3

l =4m=0

m=1

m=2

m=3

m=3

Sensitivitytotheinternalstructuredependsontheoscillationmode

21yr Time-series domain

Latestdata/plotbySalabert etal.(2017,ArXiv:1709.05110)

Relativevariationofobservablequantitywithrespecttothemean

Global-Seismology:Sun-as-a-Star /ESA-SoHol <=3

TemperatureVariationsà Relativeflux variations

VelocityVariationsà RelativeRadialvelocity variations

Latestdata/plotbySalabert etal.(2017,ArXiv:1709.05110)

Intensity

RadialVelocity

Fourier Analysis

CourtesyofHansKjeldsen.

vmax�log g

Extractionofoscillationmodeparameters&Modeidentification

Contributions to the PSD

10/30/18 ExoCafe 11

10/30/18 12

Solar-Like oscillatorsEachmodeisanindividualprobetotheinteriortothestar

Stellar Rotation & Activity

Oscillations Types & CharacterisicsTheposition intheHertzsprung-Russelldiagramallowsafirstgoodideaoftheproperties

ExcitationMechanisms

• Opacity-variations• Convectivemotion

Further,• Variationsinenergyproduction• Rotationalexcitation• Tidalexcitationinclosebinaries

Eachtypeisassociatedwithacharacteristicfrequencyrangeà Helpstoplantheobservingrun

‘Classical’heat-drivenpulsators:

• largeamplitudes(km/s)• Fastrotators>linesresolved• sinusoidalsignal(coherent)

‘solar-like’stochasticoscillators:

• smallamplitudes(m/s-cm/s)• slowrotators>unresolvedlines• Stochasticmodeexcitation(freq-

resolution,modeline-width)

Oscillations Types & CharacterisicsTheposition intheHertzsprung-Russelldiagramallowsafirstgoodideaoftheproperties

NASA TESS

Photometric and Velocity VariationsWheresolar-likeoscillationscanbedetected

Campante etal.2016,ApJ 830,138

Photometric and Velocity VariationsWheresolar-likeoscillationscanbedetected

Yu,etal.2018,MNRASLetters,480,L48

Forms of Line Profile VariationsRotationresolvesthemodeinazimuth&liftsthemodedegeneracy

Mode IDForsolar-likeoscillators

Parameters(l,±m)foragiven

oscillationmodearekeyfor

successfulasteroseismology

• Echellediagram

- Requiresacalculatedfrequencyspectrumfromatimeseries

- Searchingregularspacingoffrequencies,comb-likestructure

Requireshigh-qualitydata

(m/s!,highS/N,longtimeseries)

à PlatoSpec

Oscillation mode identificationForstarswithwellresolvedlines

Parameters(l,±m)foragiven

oscillationmodearekeyfor

successfulasteroseismology

• MomentMethod

- Timeseriesdata- Parameterizationofshapeofline- Frequencyratios

• FourierParameterFit

- 2DFourieranalysis- Extractsfourier paramter foreachmode

Bothtechniquesrequirehigh-qualitydata

(highS/N,longtimeseries)

à PlatoSpecLPV in the Fe II at 4508Å over one night on 82” CasEchelle,

McDonald observatorySchmid, Themessl, Breger, et al. (2014, A&A, 570, A33)

Frequency AliasingLet’s assume amonoperiodic star,i.e.1oscillation frequencywith3cycles/day

Theperiodogram willlook likeforforthisstarincaseof:

Continuouscoverage Periodicgags

Multi-Site Campaign

Examples for Line-Profile Variations Becketal,A&A573,A138(2015)

Coralie, Hermes, Sophie, HidesLaSilla, LaPalma,OHP, Japan

Examples for Line-Profile Variations

LPV in the Fe II at 4508Å over one night on 82” CasEchelle, McDonald observatory

Schmid, Themessl, Breger, et al. (2014, A&A, 570, A33)

ATypicaldeltaScuti:4CVn(F3V)

• Oscillationmodes:18• Rotation:Vsin I=~105km/s

~33%ofbreak-upvelocity

Photometry:

19oscillationmodes

Schmid etal.(2014)From4yearsofdata- Spectroscopy

20oscillationmodes9unseen inphotometry

Examples for Line-Profile Variations

Pulsation phase (f1)Orbital phase

SlowlypulsatingB(SPB):HD201433

(B9V)

• Oscillationmodes:~20à solidbodyrotationà rapidspinningsurface

• Triplesystem

Kallinger etal.(2017)- LPVfrommultipl.Oroscillation

- Spectroscopy

1additionalunseenmode

LPV (Fe II 423.3nm) from HERMES spectra in HD 201433 from HERMES spectra

Kallinger, Weiss, Beck et al. (2017, A&A 603, A13)

LPV in RR Lyr

Stellar Oscillation Network GroupSONGproject

- 1mTelescope, robotic- 8nodesplanned- 60.000<R<110.000- SimultaneousWavelengthref(ThAr, I2)- 440nm– 690nm- noCaHKbydefault- Readout:2,5or60seconds- V<9mag(hardwarelimited)

Optimized&dedicatedtoAsteroseismology

• long-term,time-demandingprograms(e.g.deltascuti:14days,120hrs)

• Daytimesolarobservations/helioseismology

• Studyanddiscoveryofexoplanets

Seismology with PlatoSpec

• Iscapableofdetecting- classicaloscillations- solar-likeoscillationsbutisatimedemandingproject

• Modeidentificationispossiblewithcurrentrequirements /missiongoals

• Single-Siteisnotoptimalbutdo-ableifplannedwell.àmulti-sitecampaignà couldserveasauxiliarynode

• ParallelobservationswithPLATOtoobtainsimultaneousRV,paralleltophotometry

• CaH&Kisimportanttodistinguishstellarrotation/activityfromplanets

Asteroseismology from Line-profile variations

PaulBeck

JuandelaCiervaFellowSismologia SolaryEstelaryBusquedadeExoplanetas (SSEBE)

InstitutodeAstrofisica deCanarias

34@BeckPaulG