Metallicity Study of Globular Cluster M28

Session 71 - Globular Clusters.
Display session, Wednesday, January 15
Metropolitan Ballroom,

[71.05] Metallicity Study of Globular Cluster M28

D. Kramer (UW Oshkosh, MMO), E. Barrett (Cornell, MMO), E. Friel (Boston U.), L. Fullton (STSI), S. Balachandran (U. Md)

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.

The author(s) of this abstract have provided an email address for comments about the abstract: kramed70@vaxa.uwosh.edu

Program listing for Wednesday