FIDUCIAL STELLAR POPULATION SEQUENCES FOR THE VJK{sub S} PHOTOMETRIC SYSTEM
- Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, BC, V8W 3P6 (Canada)
- Herzberg Institute of Astrophysics, National Research Council Canada, 5071 W. Saanich Rd., Victoria, BC, V9E 2E7 (Canada)
- Max-Planck-Institut fuer Astrophysik, Postfach 1317, 85748 Garching (Germany)
- Universita di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome (Italy)
- INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli (Italy)
We have obtained broadband near-infrared photometry for seven Galactic star clusters (M 92, M 15, M 13, M 5, NGC 1851, M 71, and NGC 6791) using the WIRCam wide-field imager on the Canada-France-Hawaii Telescope, supplemented by images of NGC 1851 taken with HAWK-I on the Very Large Telescope. In addition, Two Micron All Sky Survey (2MASS) observations of the [Fe/H] {approx}0.0 open cluster M 67 were added to the cluster database. From the resultant (V - J) - V and (V - K{sub S} ) - V color-magnitude diagrams (CMDs), fiducial sequences spanning the range in metallicity, -2.4 {approx}< [Fe/H] {approx}< +0.3, have been defined which extend (for most clusters) from the tip of the red giant branch (RGB) to {approx}2.5 mag below the main-sequence turnoff. These fiducials provide a valuable set of empirical isochrones for the interpretation of stellar population data in the 2MASS system. We also compare our newly derived CMDs to Victoria isochrones that have been transformed to the observed plane using recent empirical and theoretical color-T{sub eff} relations. The models are able to reproduce the entire CMDs of clusters more metal rich than [Fe/H] {approx}-1.4 quite well, on the assumption of the same reddenings and distance moduli that yield good fits of the same isochrones to Johnson-Cousins BV(RI){sub C} photometry. However, the predicted giant branches become systematically redder than the observed RGBs as the cluster metallicity decreases. Possible explanations for these discrepancies are discussed.
- OSTI ID:
- 21443171
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 140, Issue 6; Other Information: DOI: 10.1088/0004-6256/140/6/1672; ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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