AC Andromedae: the missing link between δ Scuti stars and classical Cepheids?
Abstract
The triple-mode pulsating star AC And has periods of approximately 0.71, 0.53 and 0.42 d, which have long suggested that it is an unusual (also strong-lined) RR Lyrae star. Earlier theoretical work, however, has implied that it must have a mass near 3 M0, and this has now been given strong support in an exhaustive study by Kovacs & Buchler. The most likely interpretation is that AC And is a normal post-mainsequence star in its first and only crossing of the instability strip. Assigning an absolute magnitude appropriate to an evolving 3-M0 model at the observed spectral type of about F5, and taking the 0.7 1-d period as the fundamental radial mode, AC And is found to obey the period-luminosity relation of Scuti stars and classical Cepheids, occupying a position on the relation intermediate between those two classes of star. Ways in which this might be verified are considered. Key words: stars: individual: AC And - stars: oscillations - cepheids - 6 Scuti.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- November 1994
- DOI:
- 10.1093/mnras/271.1.L19
- Bibcode:
- 1994MNRAS.271L..19F
- Keywords:
-
- Pulsating Stars: Classification;
- Pulsating Stars: Period-Luminosity Relation;
- Delta Scuti Stars: Cepheids