Variable Periods and Amplitudes in Evolved Stars
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Variable Periods and Amplitudes in Evolved Stars Dave Kilkenny University of the Western Cape South Africa
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Variable Periods and Amplitudes in Evolved Stars. Dave Kilkenny University of the Western Cape South Africa. Historical – Tony ~ 1974. “Round up the usual suspects” ~ 1979. Tony & Dave ……. Collaborative papers 1975 – 2010 n=28 - PowerPoint PPT Presentation
Transcript of Variable Periods and Amplitudes in Evolved Stars
Variable Periods and Amplitudes in Evolved Stars
Dave KilkennyUniversity of the Western Cape
South Africa
Historical – Tony ~ 1974
“Round up the usual suspects” ~ 1979
Tony & Dave ……
Collaborative papers 1975 – 2010 n=28
• AA Dor (= LB3459) 4• V652 Her (= BD+13° 3224) 4• V2076 Oph (= HD160641) 5• “EC14026” stars (= sdBV stars) 9• SDSS J160043.6+074802.9 (= sdOV star) 2
…. et al.
Stars in a close binary system
AA Dor (= LB3459 = HD269696 = …) sdOB + M?
(O-C) diagram
“Ephemeris” Tmin = T0 + n x Period
(O-C) = Observed – Calculated (Ephemeris)
AA Dor (Period = 0.261539731 d)
AA Dor JHK light curves
HW Vir
HW Vir (= BD-7° 3477) sdB + M?
HW Vir [update]
The Hydrogen-deficient star, V652 Her
V652 Her ( = BD+13° 3224)
Determined periods (day): 0.107995 1975 (Landolt)0.107827 1979-800.107790 1981
V652 Her
V652 Her
BD+10° 2179 - a new V652 Her star ?
BD+10° 2179 – NOT a new V652Her star
Hydrogen-deficient variables (Hideyuki Saio)
BX Cir (=LSS 3184)
BX Cir (= LSS3184)
BX Cir
Tmax = T₀ + nP₀ + n²k₁ + n³k₂ + n⁴k₃ + ….
V652 Her
T₀ = 2216.80425P₀ = 0.107 992 84k₁ = -44.70 x 10⁻¹⁰k₂ = +3.49 x 10⁻¹⁵k₃ = -0.53 x 10⁻²⁰
Teff = 24500 Klog g = 3.7
BX Cir
T₀ = 9477.4668P₀ = 0.106 579 86k₁ = -1.72 x 10⁻¹⁰
Teff = 23300 Klog g = 3.4
The hottest H-def star, V2076 Oph (= HD160641)
V2076 Oph
1982 data 2000 data
The pulsating sdB stars (sdBVr)
EC09582-1157 (sdBVr)
EC 09582-1157
EC 20338-1925
NY Vir (= PG 1336-018) sdBV + M?
NY Vir
NY Vir
NY Vir – orbital period change
Suggestions for future work …..
