The masses of the anomalous cepheids in the Draco system.
Abstract
From spectrophotometric observations, we have determined the mean effective temperatures of seven variable stars in the Draco dwarf spheroidal galaxy. Five of these variables are the anomalous Cepheids that do not obey the period-luminosity relations for either the classical Cepheids or the Cepheids found in globular clusters. The other two are RR Lyrae variables. The mean effective temperatures and the luminosities of the variables have been used in conjunction with the Q = P(p/p0)"2 relation to find the ratios of their masses. We find that the anomalous Cepheids have 2 to 3 times the mass of the RR Lyrae variables. We have not found a fully satisfactory explanation for the anomalous Cepheids. The only viable possibilities seem to be that they are the result of the coalescence of close binaries or are relatively young stars, 1 x 10 years old. Subject headings: galaxies: individual - stars: Cepheids - stars: RR Lyrae
- Publication:
-
The Astrophysical Journal
- Pub Date:
- November 1976
- DOI:
- 10.1086/154772
- Bibcode:
- 1976ApJ...209..734Z