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Observations of the SX Phoenicis Star XX Cygni. X.H. Yang Beijing Normal University 2010.4.1. Contents. Introduction of the SX Phe stars New observations Data reduction Light curves Analysis Conclusions. Introduction. δ Scuti Stars: 1.The SX Phoneicis stars - PowerPoint PPT Presentation
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Observations of the SX Observations of the SX Phoenicis Star XX CygniPhoenicis Star XX Cygni
X.H. YangX.H. Yang
Beijing Normal UniversityBeijing Normal University
2010.4.12010.4.1
ContentsContents
Introduction of the SX Phe starsIntroduction of the SX Phe stars New observationsNew observations Data reductionData reduction Light curvesLight curves AnalysisAnalysis ConclusionsConclusions
IntroductionIntroductionδ Scuti Stars:
1.The SX Phoneicis stars
2.High-amplitude δ Scuti Stars (HADS)
Period changes:
Period increasing and period decreasing were detected in different
δ Scuti Stars
The SX Phoenicis stars:The SX Phoenicis stars: Found in the field starsFound in the field stars Found in the blue straggler populations of Found in the blue straggler populations of
globular clustersglobular clusters short-periodshort-period Single- or multiple-mode pulsationsSingle- or multiple-mode pulsations
Importance of studying SX Phe starsImportance of studying SX Phe stars
1.Studying stellar evolution1.Studying stellar evolution
2. Potential targets for Asterseismology2. Potential targets for Asterseismology
XX Cygni:XX Cygni:
2020hh0303mm15.6 58°5715.6 58°57''17.017.0""
Spectral type: A5-F5,Spectral type: A5-F5,
VV=11.=11.mm7, P≈0.7, P≈0.dd1349, V=0.△1349, V=0.△ mm8484
Mass:1 Msun [Fe/H]=-0.49 dexMass:1 Msun [Fe/H]=-0.49 dex TTeffeff: 7530 K Radial Velocity=-108 km/s: 7530 K Radial Velocity=-108 km/s
Discovered by Ceraski (1904)Discovered by Ceraski (1904) Constant period, marked by occasional discontinuous Constant period, marked by occasional discontinuous
period changes (Szeidl & Mahdy 1981)period changes (Szeidl & Mahdy 1981) Single-mode pulsation (Hintz & Joner1997)Single-mode pulsation (Hintz & Joner1997) Both amplitude and period changes (Zhou et al. 2001)Both amplitude and period changes (Zhou et al. 2001) If the small secondary peak(maximum) is real,it is If the small secondary peak(maximum) is real,it is
transient (Blake 2002)transient (Blake 2002)
The secondary peak or maximumThe secondary peak or maximum
From BLAKE
Period Changes in SX Phoenicis Stars. II. XX Cygni
New observationsNew observations Telescope used in observationsTelescope used in observations 1. The 85-cm telescope located at the Xinglong Station 1. The 85-cm telescope located at the Xinglong Station
of NAOCof NAOC
Focal ratio: 3.27 ;Focal ratio: 3.27 ; Focal length: 2780mmFocal length: 2780mm
CCD camera: CCD,PI1024 BFTCCD camera: CCD,PI1024 BFT
Filters: Standard Johnson-Cousin-Bessel Filters: Standard Johnson-Cousin-Bessel UBVRIUBVRI
Field of view: 16Field of view: 16’’.5×16.5×16’’.5.5
2.The 60-cm telescope located in Kunming (Yunnan 2.The 60-cm telescope located in Kunming (Yunnan Astronomical Observatory)Astronomical Observatory)
Journal of new observations in Journal of new observations in VV band for XX Cyg band for XX Cyg
YearYear DateDate TelescopeTelescope FramesFrames
20072007 07.1507.15 85-cm85-cm 4242
07.1807.18 218218
07.1907.19 108108
07.2207.22 374374
07.2307.23 364364
08.1708.17 677677
08.1908.19 5757
08.2208.22 229229
08.2308.23 639639
08.2408.24 13081308
YearYear DateDate TelescopeTelescope FramesFrames
20072007 08.2708.27 85cm85cm 10691069
08.2908.29 260260
08.3008.30 992992
20082008 08.3108.31 85cm85cm 488488
20092009 07.0907.09 85cm85cm 770770
08.1108.11 684684
08.1208.12 771771
08.1308.13 472472
08.2208.22 60cm60cm 140140
08.2308.23 6565
08.2508.25 137137
YearYear DateDate TelescopeTelescope FramesFrames
20092009 10.1310.13 85-cm85-cm 830830
10.1410.14 720720
10.1710.17 598598
Totally, 24 nights of data in Totally, 24 nights of data in VV band band
Data ReductionData Reduction
Data reduction was performed using the Data reduction was performed using the APPHOT program in IRAF:APPHOT program in IRAF:
1.Bias and Dark correction, Flat fielding1.Bias and Dark correction, Flat fielding
2.Multiple aperture photometry2.Multiple aperture photometry
3.Determination of the best aperture3.Determination of the best aperture
Example of the best aperture selected:Example of the best aperture selected:
FWHM:
4 pixel
Field of view:
16’.5*16’.5
Xinglong
Light CurvesLight Curves2007
07.15-08.30
Xinglong 85cm
Error:
0.004-0.02
2008.08.2008.08.3131
XinglongXinglong
Error:Error:
0.0030.003
2009200907.0907.09-10.17-10.17XinglongXinglong
Error:Error:0.003-0.020.003-0.02KunmingKunming
60cm
Kunming
Observed new times of maximum: 37Observed new times of maximum: 37
AnalysisAnalysis
Fourier analysis:Fourier analysis:
Software: Period04
Data set: 2007.08
8 nights of observations
Frequency (dFrequency (d-1-1)) Amplitude (mmag)Amplitude (mmag) S/NS/N
ff00 7.415687.41568 343.9343.9 201.1201.1
2 f2 f00 14.8304414.83044 151.6151.6 177.7177.7
3 f3 f00 22.2466322.24663 75.675.6 122.1122.1
4 f4 f00 29.6606029.66060 38.938.9 64.864.8
5 f5 f00 37.0770137.07701 22.322.3 54.954.9
6 f6 f00 44.4924744.49247 17.517.5 47.847.8
7 f7 f00 51.9082951.90829 12.212.2 40.340.3
8 f8 f00 59.3204759.32047 9.09.0 27.727.7
9 f9 f00 66.7372766.73727 6.56.5 24.824.8
10 f10 f00 74.1538074.15380 5.45.4 13.113.1
Frequency solutions of XX Frequency solutions of XX CygCyg
Fitting curvesFitting curves
ConclusionsConclusions
No secondary peaks were found in our data.No secondary peaks were found in our data.
Next work:Next work: O-C analysis O-C analysis Period change analysisPeriod change analysis
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