Metal-rich globular clusters in the Galaxy. III. The "X-ray" globular cluster NGC 6441.
Abstract
Results are reported for UBV photoelectric and photographic observations of about 700 stars in the southern globular cluster NGC 6441 and of about 385 stars in or near the G2 globular cluster NGC 6304. Features in the color-magnitude diagrams of the clusters are found which indicate that NGC 6441 is one of the most metal-rich clusters known in the Galaxy and that NGC 6304 is a moderately metal-rich cluster. No unusual features in the color-magnitude diagram of NGC 6441 are detected that might account for its appearing in the error box of the X-ray source 3U 1746-37, except possibly the anomalous position of the variable star V6 in the diagram. Estimates are made of the foreground reddening, distance moduli, and integrated absolute visual magnitudes of both clusters. It is shown that NGC 6441 has a normal M/L ratio and is located at perigalacticon. NGC 6304 is shown to be located 450 pc above the galactic plane and possibly to contain two RR Lyrae variables.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1976
- DOI:
- 10.1086/154052
- Bibcode:
- 1976ApJ...203...97H
- Keywords:
-
- Abundance;
- Color-Magnitude Diagram;
- Globular Clusters;
- Milky Way Galaxy;
- Ubv Spectra;
- X Ray Sources;
- Cepheid Variables;
- Luminous Intensity;
- Star Distribution;
- Tables (Data);
- X Ray Astronomy;
- Astrophysics