Manganese abundances in cluster and field stars

Abstract

We have derived Mn abundances for more than 200 stars in nineteen globular clusters. In addition, Mn abundance determinations have been made for a comparable number of halo field stars possessing an overlapping range of metallicities and stellar parameters. The primary data set was comprised of high resolution spectra previously-acquired at the McDonald, Lick and Keck Observatories. Additional data were obtained from several other investigators. Data were analyzed using synthetic spectra of the 6000 Å Mn I triplet. Hyperfine structure parameters were included in the synthetic spectra computations. Our analysis shows that over the metallicity range $-0.7>[Fe/H]-2.7$ field stars have a mean relative abundance of $<[Mn/Fe]>=-0.36$ identical to that of the nineteen globular clusters $<[Mn/Fe]>=-0.36$. Our Mn abundance results viewed in conjunction with the globular cluster Cu abundances of Simmerer et al. (2003) suggest the following possibilities: one, the production of these elements is highly metallicity-dependent or two, these elements were manufactured in the Galactic halo prior to formation of present-day globular clusters.