Near infrared photometry of globular clusters - VIII. The anomalous giant branch of omega Centauri.
Abstract
Results are presented for an attempt to detect spectroscopically the approximate factor-of-five difference in metal content between two groups of stars in Omega Cen: those on the main giant branch in a two-color diagram and an anomalous group lying to the red side of that main giant branch. Radial velocities are tabulated which agree well with some previous results and which show that RGO 156 is a field star, while A271 is probably a cluster member. Analysis of CN band strengths and line spectra indicates that the anomalous stars are a strong CN group probably of high metal content and that stars with strong CN tend to lie on the red side of various two-color diagrams. It is concluded that two phenomena apparently must be invoked to account for the peculiarities of Omega Cen: mixing of reaction products to outer layers and a spread in metal abundances.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 1977
- DOI:
- 10.1093/mnras/181.3.591
- Bibcode:
- 1977MNRAS.181..591L
- Keywords:
-
- Astronomical Photometry;
- Giant Stars;
- Globular Clusters;
- Infrared Photometry;
- Infrared Spectroscopy;
- Cn Emission;
- Hertzsprung-Russell Diagram;
- Metals;
- Molecular Spectra;
- Near Infrared Radiation;
- Radial Velocity;
- Spectral Line Width;
- Astrophysics