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C. I. Johnson, C. Sneden (U. Texas, Austin), C. A. Pilachowski (Indiana U.), R. P. Kraft (U. California, Santa Cruz), I. I. Ivans (Caltech), B. Guntel (Indiana U.)
We have derived sodium and magnesium abundances for more than 100 red giant branch (RGB) stars in the Galactic globular cluster M3, using moderately high resolution (R ~ 25,000) spectra obtained with the WIYN Telescope and Hydra multi-fiber spectrograph. Temperatures for the M3 sample are based on calibrations of photometric indices, in particular V-K. Gravities, microturbulent velocities, and the overall M3 metallicity ([Fe/H] ~ -1.5) are based on the results of Sneden et al. (2004, AJ, in press). Na and Mg abundances have been determined from observed/synthetic spectrum matches of the 5682, 5688 ÅNa I lines and the 5711 ÅMg I line. The resulting M3 abundances are compared with the more detailed M3 analyses (Sneden et al. 2004) of a smaller sample of RGB stars observed at very high spectral resolution with the Keck I HIRES instrument. More importantly, the distributions of Na and Mg in M3 are contrasted with a similarly large-sample data set obtained for M13 (Pilachowski et al. 1996, AJ, 112, 545). We conclude, in agreement with the smaller-sample study, that Na and Mg have smaller star-to-star variations in M3 than in M13.
Ongoing funding from NSF, most recently in grants AST-0098453 to RPK and AST-0307495 to CS, is gratefully acknowledged. Research for III is currently supported by NASA through Hubble Fellowship grant HST-HF-01151.01-A from the Space Telescope Science Institute.
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Bulletin of the American Astronomical Society, 36 #2
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