Metal-rich globular clusters in the Galaxy. IV. A color-magnitude diagram for NGC 6304.
Abstract
From a study to V = 19.1 and B = 20.8 mag in the UBV system of 385 stars near the G2 globular cluster NGC 6304, we have found a color-magnitude diagram whose characteristics appear similar to those of 47 Tucanae, supporting the conclusion that NGC 6304 is a moderately metal-rich cluster. The reddening, E(B - V), has been estimated to be 0.58 + 0.05 mag, and the distance modulus is found, assuming Mv,HB = +0.9 + 0.2 mag, to be (m - M)0 = 13.4 + 0.2 mag. The cluster is thus 4.8 kpc from the Sun and 450 pc above the galactic plane, and it has an absolute visual magnitude of -6.8. Cluster membership of the numerous variable stars in this field remains uncertain, although one red and two possible RR Lyrae variables may be cluster members. Subject headings: clusters: globular - stars: abundances - stars: Population II
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1976
- DOI:
- 10.1086/154053
- Bibcode:
- 1976ApJ...203..113H