Chemical abundance analysis of the old, rich open cluster Trumpler 20

Abstract

Aims. Trumpler 20 is an open cluster located at low Galactic longitude, just beyond the great Carina spiral arm, and whose metallicity and fundamental parameters were very poorly known until now. As it is most likely a rare example of an old, rich open cluster – possibly a twin of NGC 7789 – it is useful to characterize it. To this end, we determine here the abundance of several elements and their ratios in a sample of stars in the clump of Trumpler 20.