Evolutionary increase in the nitrogen abundance in the atmospheres of early B stars
The nitrogen abundance in the atmospheres of 36 stars of the spectral classes B0-B3 and luminosity classes V-III was evaluated in order to test the tenet of stellar evolution that mixing occurs in a massive star no sooner than when it enters the supergiant phase. The nitrogen abundance in the atmosphere and the mass and age of the star were obtained from the effective temperature and the acceleration due to gravity in the atmosphere; the assumption of local thermodynamic equilibrium was omitted. For all three mass groups tested, the nitrogen abundance increased with increasing time. The rate of increase depended strongly on the mass, and the larger the mass, the faster the growth in abundance. The rate of increase was smooth, indicating that the products of the CNO cycle may be carried into the surface layers of B stars during the main sequence stage. 34 references.
- Research Organization:
- Krymskaia Astrofizicheskaia Observatoriia, Nauchny, Ukrainian SSR
- OSTI ID:
- 5827932
- Journal Information:
- Astrophysics (Engl. Transl.); (United States), Vol. 20
- Country of Publication:
- United States
- Language:
- English
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