Absolute ultraviolet spectrophotometry from the TD-1 satellite: flux distribution of helium weak stars.
Abstract
Summary. Spectrophotometric observations of25 helium weak B stars, including faint objects in the Orion association, have been obtained with the S 2/68 experiment on board of the TD-1 satellite in the spectral range 1400-2550 A. An "ultraviolet spectral type" corresponding to the observed energy distribution has been determined for each star from independent methods, and it is compared with the photometric and spectroscopic ground based determinations. Many sample stars appear to have normal fluxes when compared with standard stars of the same UBV colors. Other stars (about 40 %) are however underluminous in the ultraviolet region and the influence of line blocking is discussed. A possible sequence of increasing chemical peculiarity between helium weak and Bp stars could be suggested from these data. Two possible spectrum variables are also indicated. Key words: helium abundance - stellar spectra - ultraviolet observations - peculiar stars
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- October 1978
- Bibcode:
- 1978A&A....69..171C
- Keywords:
-
- B Stars:Helium;
- B Stars:UV Spectra;
- Peculiar B Stars:Spectrum Variables