Variability Study of the δ Scuti Star UY Cam and the Eclipsing Binary CD Cam

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Variability Study of the δ Scuti Star UY Cam and the Eclipsing Binary CD Cam. 2010-04-01 Kailin Pan Beijing Normal University. Characteristics of δ Scuti Stars. short periods: ~ 0.02 – 0.25 day amplitudes: < 1 mag masses: ~1.5 - 2.5 Msun spectral type: A5 - F2. - PowerPoint PPT Presentation

Transcript of Variability Study of the δ Scuti Star UY Cam and the Eclipsing Binary CD Cam

  • Variability Study of the Scuti Star UY Cam and the Eclipsing Binary CD Cam2010-04-01 Kailin PanBeijing Normal University

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  • Characteristics of Scuti Starsshort periods: ~ 0.02 0.25 dayamplitudes: < 1 mag masses: ~1.5 - 2.5 Msun spectral type: A5 - F2. found on the intersection of the classical instability strip and the main sequence in the Hertzsprung-Russell diagramexcitation mechanism: mechanism*

  • LADS and HADSLow amplitude Scuti Star (LADS) - more in number - amplitudes: mmag to a few tens of a mmag - pulsation mode: non-radial p modeHigh amplitude Scuti Star (HADS) - less in number - amplitudes: > ~0.3 mag - pulsation mode: radial mode

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  • Importance of Studying Scuti StarTo test the theory of stellar evolutionFor asterseismology to apply*

  • Previous Studies of UY Camdiscovered by Baker(1937) to be a variable star - period ~ 6.16 days + shape of lightcurves Cepheid variableWillams (1964): - amplitude ~ 0.45 mag + period ~ 0.267 day c RR Lyrae star - disperion of points in the lightcurves possible cycle-to-cycle changesBeyer(1966) - no changes in the period - varying amplitude ~ 0.17 0.5 mag - Instability in the lightcurves found by Williams and Beyer two or more pulsation modesBroglia & Conconi (1992): - no evidence of instability

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  • Our WorkTo investigate the period changes of UY Cam To check the existence of the secondary pulsation mode*

  • UY Cam = 07h58m59s = 72.79V ~ 11.7 magObservations (Xinglong 85-cm /50-cm): I: Nov 2007II: Feb 2008III: Mar 200819 days in V band *

  • Light Curves 1st PeriodError: ~ 0.003 0.0062007 NovXinglong 85-cm telescope

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  • Light Curves 2nd PeriodError: ~ 0.005 0.012008 FebXinglong 85-cm/ 50-cm telescope

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  • Light Curves 3rd PeriodError: ~ 0.004 0.0072008 MarXinglong 85-cm telescope

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  • Pulsation AnalysisPeriod04data used: 2nd period of observationOnly fundamental frequency f0 : 3.744 /day5 harmonics detected (2f0, 3f0, 4f0, 5f0, 6f0)

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  • Results of Fitting*1st Period2nd Period3rd Period

  • Times of Maximum Light47 times of maximum light in total (13 from our work)Time span ~ 60 yearsNew ephemeris formular - HJDmax = 2432144.4377 + 0.267041135 x E - T0 = 0.003 day, P = 0.000000045 day

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  • O - C Analysiscyclic variation binary systemquadratic plus a sine function (light travelling time effect)

    semi-amplitude = 2557.7 s; P =0.26704121 day; = (-0.169 +/- 0.483) x 10^-11 day; Porb = 49.2 yr

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  • Mass of Companiona1 sin i= 5.12 AUf (m) = (a1 sin i )^3 / Porb = 0.0554f(m) = (m2 sin i )^3/(m1 + m2)^2 m1=2Msun (Zhou & Liu 2003) (m1 = mass of UY Cam)a1/a2 = m2/m1 Min mass of companion : 0.75 Msun

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  • CD CamEclipsing binary of W UMa type V ~ 12.02 magDiscovered by Broglia & Conconi (1992) - period ~ 18 hours - amplitude ~ 0.2mag

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  • Lightcurves of CD Cam*

  • Phase Diagram of CD Cam*

  • Times of Minimum Light14 times of maximum light in total (8 from our work)Time span ~ 23 yearsNew ephemeris formular -HJDmax = 2446170.055 + 0.7641868 x E - T0 = 0.002 day, P = 0.0000002 day,

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  • O C Diagram of CD Cam*

  • Conclusions UY CamP = 0.267041135 dayMonoperiodic (fundamental frequency: 3.744/day)Cyclic variation in O C diagram detection of companion - mass > 0.75 Msun - Porb = 49.2 years CD CamP = 0.7641868 day

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