Elemental Abundances in Evolved Supergiants. II. The Young Clusters [CLC]h[/CLC] and χ Persei

Abstract

We report on the results of our analyses of high-quality spectra of M supergiants in the h and chi Persei double cluster. Our temperature estimates range from 3500 to 4000 K for a sample of 14 stars. There is a wide range in the lithium abundances, from [Li/Fe]=-1.7 to [Li/Fe]=-0.10. The 12C/13C ratio ranges from 10 to 16 and displays a weak trend with luminosity, such that the more luminous stars have a slightly smaller ratio. We find a significant excess of Na, which may be due to its production by proton capture by 22Ne. However, there is no evidence for the O deficiency that usually accompanies a Na excess in globular cluster stars.