Nitrogen Abundances in Giant Stars of the Globular Cluster NGC 6752

Abstract

We present N abundances for 21 bright giants in the globular cluster NGC 6752 based on high-resolution UVES spectra of the 3360 8NH lines.We confirm that the Stro¨mgren c1 index traces the N abundance and find that the star- to-star N abundance variation is 1.95 dex, at the sample’s luminosity. We find statistically significant correlations, but small-amplitude variations, between the abundances ofN and ?-, Fe-peak, and s-process elements. Analyses using model atmospheres with appropriate N, O, Na, and Al abundances would strengthen, rather than mute, these correlations. If the small variations ofheavy elements are real, then the synthesis of the N anomalies must take place in stars which also synthesize ?-, Fe-peak, and s-process elements. These correlations offer support for contributions from both asymptotic giant branch and massive stars to the globular cluster abundance anomalies. Subject