AAS 205th Meeting, 9-13 January 2005
Session 23 Globular Clusters in and around the Milky Way
Poster, Monday, January 10, 2005, 9:20am-6:30pm, Exhibit Hall

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[23.04] A CN Band Survey of Red Giants in the Globular Cluster M53

S.L. Martell, G.H. Smith (Dept. of Astronomy & Astrophysics, UCO/Lick Observatory, UC Santa Cruz)

We investigate the star-to-star variations in \lambda3883 CN bandstrength among red giant stars in the low-metallicity globular cluster M53 ([Fe/H] = --2.0). Our data were taken with the Kast spectrograph on the 3-meter Shane telescope at Lick Observatory in April 2001. Star-to-star variations in CN bandstrength are common in intermediate- and high-metallicity globular clusters ([Fe/H] \geq --1.6). Our data were obtained to test whether that variation will also be present in a low-metallicity globular cluster, or whether it will be suppressed by the overall lack of metals in the stars. Our preliminary result is that the \lambda3883 CN band is weak in our program stars, which span the brightest magnitude of the red giant branch. On visual inspection, the M53 giants appear to be similar in their CN bandstrength to the four CN-weak giants in NGC 6752 whose average spectrum is plotted in Fig. 4 of Norris et al. (1981, ApJ, 244, 205). This work is planned to form part of a larger study of the metallicity dependence of CN bandstrength and carbon abundance behavior on the upper giant branch of globular clusters. This work is supported by NSF grant AST 00-98453 and by an award from the ARCS foundation, Northern California Chapter.

The author(s) of this abstract have provided an email address for comments about the abstract: martell@ucolick.org

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