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Session 72 - Open Clusters.
Display session, Wednesday, January 15
The ages and distance moduli for the old open clusters NGC 2204, Berkeley 39, NGC 2477, and Melotte 66 are constrained by comparing the observed cluster color-magnitude diagrams to theoretical models developed by Bertelli et al. (1994, Aamp;A, 106, 235). For each cluster, a best fitting model is selected based not only on the match to an observed color-magnitude diagram but also on the isochrones agreement with adopted values of the cluster's metallicity and reddening. Based on the best fitting models, NGC 2204 is 1.6^+0.9_-0.3 Gyrs old with (m-M)_o = 13.0^+0.5_-0.4, Berkeley 39 has an age of 6^+2_-1 Gyrs with (m-M)_o = 12.9\pm0.2, NGC 2477 is 1^+0.3_-0.2 Gyr old with (m-M)_o = 10.5^+0.4_-0.3, and Melotte 66 has an age of 4\pm1 Gyrs with (m-M)_o = 13.2^+0.3_-0.1. Using the same data, we have begun an examination of the cluster luminosity functions and density profiles.
Program listing for Wednesday