A photometric study of the X-ray globular cluster NGC 6624.
Abstract
This paper presents a revised color-magnitude diagram of NGC 6624, a globular cluster coincident with the bursting X-ray source 3U 1820-30. The horizontal branch lies at V = 16.05 mag; with the adopted reddening of 0.25 mag, a revised distance of 8.3 + or - 1.2 kpc is determined. The m/H index derived from the slope of the giant branch is -0.7, which makes NGC 6624 one of the more metal-rich clusters in the Galaxy. The one RR Lyrae variable star in the area may be a field star; a red variable near the cluster is probably a member.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1978
- DOI:
- 10.1086/156386
- Bibcode:
- 1978ApJ...224..383L
- Keywords:
-
- Astronomical Photometry;
- Globular Clusters;
- X Ray Sources;
- Color-Magnitude Diagram;
- Extinction;
- Main Sequence Stars;
- Milky Way Galaxy;
- Stellar Luminosity;
- Tables (Data);
- Ubv Spectra;
- Astronomy;
- C-M Diagrams:Globular Clusters;
- Globular Clusters:Photometry;
- Globular Clusters:X-Ray Sources