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Session 71 - Globular Clusters.
Display session, Wednesday, January 15
We have obtained high resolution echelle spectroscopic data for two red giant stars in the globular cluster M28. M28(NGC 6626; l =7.8\deg, b \rm=-5.6\deg) is a poorly studied globular cluster (age of 14 Gyrs) with disk-like kinematics. Previous metallicity estimates span a range from [Fe/H] = -1.9\pm0.4 to -1.0\pm0.2. This is surprising, since most disk objects are relatively metal-rich. The data, taken with the CTIO 4m telescope, cover a wavelength range of 5300-8400Åwith a pixel resolution of 0.07ÅAnalysis of the spectroscopic data yields an average metallicity of [Fe/H] = -1.45\pm0.04. Analyses were done using MOOG and Kurucz Model Atmospheres. Radial velocities for the two red giants were also measured, but as M28 has a large internal velocity dispersion, no conclusive results about the cluster could be drawn. This research was supported by the National Science Foundation (REU grant AST-9300391) and the Perkin Fund.
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