The color-magnitude diagram of the globular cluster M 92
Abstract
Color indices and photovisual magnitudes of more than I 100 stars in the globular cluster Messier 92 were determined by a combination of photoelectric and photographic measures, the former providing a standard sequence and the latter being used for interpolation. The resulting color-magnitude diagram extends from the top of the red giant branch at absolute photovisual magnitude -3 to a segment of the main sequence at +4 and shows how the giant sequences join the main sequence of a globular cluster. Points representing the mean magnitudes and color indices of six cluster-type variables were found to fall within a distinct gap in the horizontal branch between P - V = +0.12 and +0.23 mag., which is completely devoid of non-variable stars.
- Publication:
-
The Astronomical Journal
- Pub Date:
- February 1953
- DOI:
- 10.1086/106800
- Bibcode:
- 1953AJ.....58....4A