S316p.11 — The Spatial Distributions of Red Giants in the Distant Galactic Globular Cluster NGC2419 as Seen in Eight Colors

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Aug 10th at 6:00 PM until 7:30 PM




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Author(s): Stephen D Gillam1

Institution(s): 1. Indiana University Purdue University Fort Wayne

I present the results of a study of the radial variations of the ratio of the two populations of stars in the galactic globular cluster NGC2419 as seen in eight broad-band, HST/WFC3 colors. The populations are identified as a metal-poor first generation (FG) with an age of 12 Gyr and a relatively metal-rich, oxygen and helium-rich, second generation (SG), with an age of 10 Gyr. Synthetic color-magnitude diagrams of NGC2419 are used to determine the fractions of the present-day stellar population that are FG and SG stars. The distance modulus of this cluster and the color excess, E(B-V), are estimated from consistent fits of stellar evolutionary models to eight color-magnitude diagrams. It is shown that the signature of two stellar generations can be clearly seen in the population ratio profiles. This is the first time Hubble Legacy Archive source catalogs (as opposed to the original images) have been used to study a globular cluster.