A NEW LOOK AT THE OLD STAR CLUSTER NGC 6791
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States)
- Yerkes Observatory, University of Chicago, Williams Bay, WI 53191 (United States)
- Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
- Astrophysics Group, Lennard-Jones Laboratories, Keele University, Keele, Staffordshire ST5 5BG (United Kingdom)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- Canada-France-Hawaii Telescope Corporation, Kamuela, HI 96743 (United States)
We present comprehensive cluster membership and g'r' photometry of the prototypical old, metal-rich Galactic star cluster NGC 6791. The proper-motion catalog contains 58,901 objects down to g'{approx} 24, limited to a circular area of radius 30'. The highest precision of the proper motions is 0.08 mas yr{sup -1}. Our proper motions confirm cluster membership of all main and also some rare constituents of NGC 6791. The total number of probable cluster members down to g' = 22 (M{sub V} {approx} +8) is {approx}4800, corresponding to M{sub tot} {approx} 5000 M{sub sun}. New findings include an extended horizontal branch in this cluster. The angular radius of NGC 6791 is at least 15' (the effective radius is R{sub h} {approx_equal} 4.'4 while the tidal radius is r{sub t} {approx_equal} 23'). The luminosity function of the cluster peaks at M{sub g}{sup '}{approx}+4.5 and then steadily declines toward fainter magnitudes. Our data provide evidence that differential reddening may not be ignored in NGC 6791.
- OSTI ID:
- 21562682
- Journal Information:
- Astrophysical Journal Letters, Vol. 733, Issue 1; Other Information: DOI: 10.1088/2041-8205/733/1/L1; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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