Possible causes for wide depresssion appearance in ultraviolet spectra of B- and A-stars. I. Abundance anomalies in stellar atmospheres.
A brief survey of observational data related to energy distribution in UV spectra of hot stars is presented, indicating wide depression for a part of normal B- and A-stars and particularly for Ap-stars. The observed depressions may be connected with the overabundance of elements in stellar atmospheres. To check this assumption synthetic spectra in three UV intervals (2350 - 2380), 2245 - 2275 and 1810 - 1840 Å) and one optical interval (4500 - 4530 Å) are calculated for different element abundances in stellar atmospheres. It was shown that UV flux deficiency for Ap-stars can be explained by the metal overabundance intrinsic for such stars. In the case of normal stars permissible variations of metal abundances may explain the appearance of UV flux deficiency (or its excess) for A-stars and probably for latest B-stars. This mechanism fails at higher temperatures.
Izvestiya Ordena Trudovogo Krasnogo Znameni Krymskoj Astrofizicheskoj Observatorii
- Pub Date:
- Stellar Atmospheres: Synthetic Spectra;
- Stellar Atmospheres: Element Abundances;
- Hot Stars: UV Spectra;
- Ap Stars: UV Spectra