[23.06] C and N Abundances in Stars At the Base of the Red Giant Branch in M15

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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[23.06] C and N Abundances in Stars At the Base of the Red Giant Branch in M15

J. G. Cohen (Caltech), M. M. Briley (University of Wisconsin Oshkosh and NSF), P. B. Stetson (Herzberg Institute of Astrophysics)

We present an analysis of a large sample of moderate resolution Keck LRIS spectra of subgiant (V ~ 17.5 mag) stars in the galactic globular cluster M15 with the goal of deriving C and N abundances. We use the CH and NH bands respectively. Star-to-star stochastic variations with significant range in both [C/Fe] and [N/Fe] are found at all luminosities. The C and N abundances appear to be anti-correlated.

We describe the implications of our long term work in this area, now covering M71, M5, M13 and M15, in terms of the star formation history and chemical evolution of galactic globular clusters.

This work was supported in part by NSF grant AST-0205951 to JGC.

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