A model-atmosphere analysis of the spectrum of Arcturus.
Abstract
The spectrum of the high-velocity red giant, alpha Boo (Arcturus), is analyzed relative to that of the sun, using spectral-line data from the Arcturus Atlas and a differential technique employing empirical atmospheric models for both stars. The line data and several photometric observations are used to determine the effective temperature and the surface gravity, and a very low mass (between 0.1 and 0.6 solar mass) is calculated, implying a substantial mass loss. The chemical composition of the red giant is determined from the atomic, ion, and molecular lines of 32 elements, and an average underabundance of about a factor of 4 is found along with a significantly different abundance pattern than the sun's. Evidence is presented which indicates that Arcturus is not in the first giant phase following the main sequence, but is a more evolved star which may have experienced the helium flash.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- January 1975
- Bibcode:
- 1975A&A....38..239M
- Keywords:
-
- Astronomical Models;
- Atmospheric Models;
- Giant Stars;
- Spectrum Analysis;
- Stellar Atmospheres;
- Stellar Mass;
- Absorption Spectra;
- Abundance;
- Astronomical Photometry;
- Atomic Spectra;
- Chemical Composition;
- Data Acquisition;
- Line Spectra;
- Molecular Spectra;
- Stellar Motions;
- Astrophysics