Oxygen abundances in halo giants. II - Giants in the globular clusters M13 and M3 and the intermediately metal-poor halo field

Abstract

Oxygen, sodium, iron, vanadium, and scandium abundances are derived for giants in the intermediately metal-poor globular clusters M 3 and M 13 and for giants of comparable metallicity in the local halo field. The data are obtained from Lick Observatory Hamilton Echelle spectra centered on the [O I] doublet. For M13 we derive = -1.51 ± 0.01 from 13 giants with a range of 500 K in effective temperature. For M3, we find = -1.47 ± 0,01, from seven stars with a range of 300 K in effective temperature. There is no compelling evidence for star-to-star variations in [Fe/H] in either cluster