Evolutionary effects on the surface abundances of an early-type supergiant.
Abstract
Line-blanketed model atmospheres of the two supergiants HD 148379 and HD 157038 are used in an LTE abundance analysis which indicates that nitrogen may be overabundant in the former, by comparison with both the latter and with the sun, by a factor of about 6. Since the two supergiants have similar bolometric magnitudes and lie close together in the HR diagram, it is suggested that their evolutionary histories differ. The (probably more evolved) HD 157038 may have passed through a red supergiant phase, when high mass loss and/or deep convection revealed the products of the CNO bicycle at its surface; the star may then have evolved bluewards in the HR diagram, to appear again as a nitrogen- and helium-rich blue supergiant in the relatively slow evolutionary stage of core helium burning.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1986
- Bibcode:
- 1986A&A...155...79L
- Keywords:
-
- Abundance;
- B Stars;
- Stellar Atmospheres;
- Stellar Composition;
- Stellar Evolution;
- Supergiant Stars;
- Blue Stars;
- Early Stars;
- Hertzsprung-Russell Diagram;
- Red Giant Stars;
- Spectral Line Width;
- Stellar Spectra;
- Thermodynamic Equilibrium;
- Astrophysics