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 …..