The Unusual Horizontal Branch of NGC 2808
Abstract
A new color-magnitude diagram for the southern globular cluster NGC 2808 shows a peculiar "split" horizontal branch: both red and extremely blue HB stars are present, but a large unpopulated gap exists between them in the color range - 0.1 < (B - V)0 <0.4. The cluster's giant-branch morphology and red HB are normal for a moderately high-metallicity object, but the presence of the extremely blue [(B - V)0 < -0.1] HB stars is anomalous. This feature is interpreted as due to a possible discontinuous mass distribution along the horizontal branch. Subject headings: globular clusters - horizontal-branch stars
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1974
- DOI:
- 10.1086/181616
- Bibcode:
- 1974ApJ...192L.161H