Ultraviolet and optical studies of binaries with luminous cool primaries and hot companions. I. Intrinsic colors and newly recognized systems.
Abstract
The use of space satellites makes it possible to observe the middle and far-ultraviolet wavelengths where the hot component of the binary dominates, and to derive its properties directly. The considered investigation is concerned with seven probable hot companions noticed in UV flux catalogs. Intrinsic ultraviolet colors have been determined for luminous cool stars with the objective to separate accurately the effects of the hot and cool components. The seven considered systems include My Per A, Ny Her, Beta Sct, 22 Vul, 35 Cyg, Xi Cyg, and HR 8157. Their properties are presented in a table. A computer program calculates synthetic energy distributions for virtually any combination of spectral types, visual magnitudes, and reddening. These are then fit to observed energy distributions by trial and error. In all cases, except perhaps Beta Sct, the obtained absolute magnitudes of the hot companions are consistent with main-sequence stars and lend support to the supposition that the hot objects are physically associated with the primaries.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 1981
- DOI:
- 10.1086/159066
- Bibcode:
- 1981ApJ...247..560P
- Keywords:
-
- Binary Stars;
- Late Stars;
- Stellar Temperature;
- Supergiant Stars;
- Ultraviolet Astronomy;
- Companion Stars;
- Computer Programs;
- Cool Stars;
- Hot Stars;
- Spectral Energy Distribution;
- Stellar Luminosity;
- Ultraviolet Spectra;
- Astronomy