Survey for Transiting Extrasolar Planets in Stellar Systems. I. Fundamental Parameters of the Open Cluster NGC 1245
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abstract
We derive fundamental parameters for the old, rich, open cluster NGC 1245 using BVI photometry from the MDM 1.3 m and 2.4 m telescopes. Based on detailed isochrone fitting, we find that NGC 1245 has a slightly subsolar metallicity, [Fe/H] = -0.05 0.03 (statistical) 0.08 (systematic) and an age of 1.04 0.02 0.09 Gyr. In contrast to previous studies, we find no evidence of significant differential reddening. We determine an extinction of AV = 0.68 0.02 0.09 mag and a distance modulus of (m - M)0 = 12.27 0.02 0.12 mag, which corresponds to a distance of 2.8 0.2 kpc. We derive a logarithmic mass function slope for the cluster of = -3.12 0.27, where a Salpeter slope is = -1.35. Fits to the radial surface density profile yield a core radius of rc = 3.10 0.52 (2.57 0.47 pc). NGC 1245 is highly relaxed and contains a strongly mass-segregated population. The mass function for the inner cluster has a very shallow slope, = -0.56 0.28. In contrast, the outer periphery of the cluster is enriched with low-mass members and devoid of high-mass members out to the tidal radius, rt = 20 (16.5 pc). Based on the observed surface density profile and an extrapolated mass function, we derive a total cluster mass, M = 1300 90 170 M.
