Period changes in the pulsating extreme helium stars V652 Her and BX Cir
Abstract
Thirty-four new timings of maxima of the radially pulsating extreme helium (EHe) star V652 Her (= BD+13° 3224) obtained during 1996-2004 are reported. The quartic ephemeris (for the pulsation period decrease) is extended and the higher-order terms are defined more accurately. We also report 45 new timings of maxima for the closely similar star BX Cir (= LSS 3184) over the same baseline and present the first evidence that this star also shows a decreasing period. The data obtained thus far can be represented by a quadratic ephemeris - a linearly decreasing period in BX Cir - though the decrease rate (dP/dn~ 3.7 × 10-10 d) is much smaller than in V652 Her.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- August 2005
- DOI:
- 10.1111/j.1365-2966.2005.09188.x
- Bibcode:
- 2005MNRAS.361..559K
- Keywords:
-
- stars: chemically peculiar;
- stars: individual: BX Cir;
- stars: individual: V652 Her;
- stars: oscillations;
- stars: variables: other