The variable shell star HR 5999 and its environment.
Abstract
VBLUW photometric observations of the variable shell star HR 5999, its binary companion HR 6000, and several other stars in their vicinity are reported. The extinction of the light from HR 5999 is shown to be partly due to dust located in a circumstellar envelope, ratios of total-to-selective absorption are determined, and the foreground extinction is estimated as 0.20 magnitude. The distance of the visual binary system Delta 199 (HR 5999 plus HR 6000) is calculated as approximately 270 pc, an absolute visual magnitude of -0.9 is obtained for HR 5999, and an effective temperature of 8500 K is derived. The extinction law for the dust grains in the circumstellar shell is analyzed, and the evolutionary status of HR 5999 is considered. A best fit to Larson's (1972) pre-main-sequence evolutionary tracks is found for a protostar of 3 solar masses with a radius of 7 solar radii and an initial interstellar-cloud temperature and density of 10 K and 10 to the -20th power g/cu cm, respectively; the age of the protostar is estimated to be about 750,000 yr.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1978
- Bibcode:
- 1978A&A....62..439T
- Keywords:
-
- A Stars;
- Shell Stars;
- Stellar Envelopes;
- Stellar Spectrophotometry;
- Ubv Spectra;
- Variable Stars;
- Visual Photometry;
- Astrometry;
- Binary Stars;
- Cosmic Dust;
- H Alpha Line;
- Interstellar Extinction;
- Stellar Evolution;
- Stellar Magnitude;
- Stellar Temperature;
- T Tauri Stars;
- Astrophysics;
- Peculiar A Stars:Walraven Photometry;
- Shell Stars:Walraven Photometry