Spectra with a high signal-to-noise ratio of 79 stars that are just below the main-sequence turnoff of M71 are presented. They yield indices for the strength of the G band of CH and the ultraviolet CN band at 3885 Å. These indices are each to first-order bimodal and they are anticorrelated. There are approximately equal numbers of CN-weak/CH-strong and CN-strong/CH-weak main-sequence stars in M71. It is not yet clear whether these star-to-star variations arise from primordial variations or from mixing within a fraction of individual stars as they evolve.
The Astronomical Journal
- Pub Date:
- May 1999
- GALAXY: GLOBULAR CLUSTERS: GENERAL;
- GALAXY: GLOBULAR CLUSTERS: INDIVIDUAL: MESSIER NUMBER: M71;
- STARS: EVOLUTION;
- Accepted for publication in the AJ to appear back to back with paper I. 14 pages with 5 figures