The main sequence of the globular cluster NGC 6752.
Abstract
UBV photoelectric and photographic photometry of the southern globular cluster NGC 6752 are presented. The photoelectric sequence is extended to a point about 1 mag below the main-sequence turnoff. A cluster color-magnitude diagram, uncorrected for reddening, is plotted which shows that: (1) the RR Lyrae gap is unpopulated except for one short-period W Vir star that lies above the horizontal branch; (2) the horizontal-branch stars apparently lie mostly to the blue of the instability strip; (3) the slope of the giant branch is about 5.0, implying an intermediate metal deficiency; (4) the main-sequence turnoff occurs at V = 17.30 + or - 0.05 and B-V = 0.425 + or - 0.010; (5) the main sequence appears to be very broad, probably as a result of errors in the photographic photometry; and (6) the normalized UV excess of the main-sequence stars is 0.22 mag, indicative of a metallicity (Fe/H) of about -1.5.
- Publication:
-
The Astronomical Journal
- Pub Date:
- April 1979
- DOI:
- 10.1086/112444
- Bibcode:
- 1979AJ.....84..515C
- Keywords:
-
- Astronomical Photometry;
- Electrophotometry;
- Globular Clusters;
- Hertzsprung-Russell Diagram;
- Ubv Spectra;
- Color-Magnitude Diagram;
- Interstellar Extinction;
- Main Sequence Stars;
- Spectrograms;
- Tables (Data);
- Astrophysics;
- DDO Photometry:Globular Clusters;
- Globular Clusters:Main-Sequence Stars;
- Globular Clusters:Metal Abundances;
- Globular Clusters:UBV Photometry;
- Globular Clusters:UV Excesses