Intrinsic colours and physical properties of Cepheids.
Abstract
Reddening-free colors and VBLUW color excesses are determined for 170 Southern Hemisphere galactic Cepheids. The Cepheid colors are corrected for interstellar reddening, the VBLUW color excesses are compared with color excesses obtained in other studies of Cepheids, and physical properties are derived by comparing the reddening-free colors with theoretical colors previously computed from a grid of model-atmosphere fluxes. The cyclic behavior of temperature, gravity, luminosity, and radius is calculated along with the equilibrium values of these quantities for 98 Cepheids with periods shorter than 11 days. It is found that at least 25% of the Cepheids studied show evidence of a binary companion and that the computed velocity curves are in reasonable agreement with observed radial-velocity curves. It is concluded that the use of hydrostatic-equilibrium model atmospheres is not too unrealistic for the continuum colors of Cepheids.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1978
- Bibcode:
- 1978A&A....62...75P
- Keywords:
-
- Cepheid Variables;
- Physical Properties;
- Southern Hemisphere;
- Stellar Spectrophotometry;
- Atmospheric Models;
- Binary Stars;
- Light Curve;
- Radial Velocity;
- Astrophysics;
- Cepheids:Colors;
- Photometric Systems:Walraven Photometry