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Variable Periods and Amplitudes in Evolved Stars

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

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Variable Periods and Amplitudes in Evolved Stars

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  1. Variable Periods and Amplitudes in Evolved Stars Dave Kilkenny University of the Western Cape South Africa

  2. Historical – Tony ~ 1974

  3. “Round up the usual suspects” ~ 1979

  4. 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

  5. …. et al.

  6. Stars in a close binary system

  7. AA Dor (= LB3459 = HD269696 = …) sdOB + M?

  8. (O-C) diagram “Ephemeris” Tmin = T0 + n x Period (O-C) = Observed – Calculated (Ephemeris)

  9. AA Dor (Period = 0.261539731 d)

  10. AA Dor JHK light curves

  11. HW Vir

  12. HW Vir (= BD-7° 3477) sdB + M?

  13. HW Vir [update]

  14. The Hydrogen-deficient star, V652 Her

  15. V652 Her ( = BD+13° 3224) Determined periods (day): 0.107995 1975 (Landolt) 0.107827 1979-80 0.107790 1981

  16. V652 Her

  17. V652 Her

  18. BD+10° 2179 - a new V652 Her star ?

  19. BD+10° 2179 – NOT a new V652Her star

  20. Hydrogen-deficient variables (Hideyuki Saio)

  21. BX Cir (=LSS 3184)

  22. BX Cir (= LSS3184)

  23. BX Cir

  24. Tmax = T₀ + nP₀ + n²k₁ + n³k₂ + n⁴k₃ + …. V652 Her BX Cir T₀ = 9477.4668 P₀ = 0.106 579 86 k₁ = -1.72 x 10⁻¹⁰ Teff = 23300 K log g = 3.4 T₀ = 2216.80425 P₀ = 0.107 992 84 k₁ = -44.70 x 10⁻¹⁰ k₂ = +3.49 x 10⁻¹⁵ k₃ = -0.53 x 10⁻²⁰ Teff = 24500 K log g = 3.7

  25. The hottest H-def star, V2076 Oph (= HD160641)

  26. V2076 Oph 1982 data 2000 data

  27. The pulsating sdB stars (sdBVr)

  28. EC09582-1157 (sdBVr)

  29. EC 09582-1157

  30. EC 20338-1925

  31. NY Vir (= PG 1336-018) sdBV + M?

  32. NY Vir

  33. NY Vir

  34. NY Vir – orbital period change

  35. Suggestions for future work …..

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