A&A 492, 823-831 (2008)
DOI: 10.1051/0004-6361:200810098
NLTE abundances of Mn in a sample of metal-poor stars
M. Bergemann and T. GehrenInstitute for Astronomy and Astrophysics, Ludwig-Maximilian University, Scheinerstr. 1, 81679 Munich, Germany
e-mail: masha@rejoin.net
Received 30 April 2008 / Accepted 3 October 2008
Abstract
Aims. Following our solar work, we perform NLTE calculations of the Mn abundance for
fourteen stars with [Fe/H] from 0 to –2.5, mainly to show how NLTE affects Mn
abundances in cool stars of different metallicities.
Methods. The spectrum synthesis and Mn abundances are based on statistical equilibrium
calculations using various estimates for the influence of hydrogen collisions.
Results. The NLTE abundances of Mn in all studied stars are systematically higher than
the LTE abundances. At low metallicities, the NLTE abundance corrections may
run up to 0.5–0.7 dex. Instead of a strong depletion of Mn relative to Fe in
metal-poor stars as found by the other authors, we only find slightly subsolar
values of [Mn/Fe] throughout the range of metallicities analyzed
here.
Conclusions. The [Mn/Fe] trend in metal-poor stars is inconsistent with the predictions
of galactic chemical evolution models, where Mn is less produced than Fe.
Key words: line: profiles -- line: formation -- stars: abundances -- nuclear reactions, nucleosynthesis, abundances
© ESO 2008

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