Bibcode
Ramirez, I.; Allende Prieto, C.; Lambert, D. L.
Referencia bibliográfica
American Astronomical Society Meeting 205, #52.12; Bulletin of the American Astronomical Society, Vol. 36, p.1424
Fecha de publicación:
12
2004
Número de citas
0
Número de citas referidas
0
Descripción
Oxygen abundances for a large sample of dwarf stars in the Galactic thin
and thick disks are determined from a non-LTE analysis of the oxygen
triplet lines at 777 nm. Kinematic criteria are employed to determine
whether a star belongs to the thin or thick disk. Temperatures are
obtained from photometric calibrations based on the infrared flux method
and surface gravities from Hipparcos parallaxes and stellar evolution
calculations. High resolution spectra from the HET and the 2.7 m
telescopes at McDonald Observatory, and the VLTI-UVES archive are used.
Metallicities are derived from relatively unblended Fe I and Fe II lines
for which reliable laboratory gf values are available. Oxygen abundances
are obtained from the triplet lines at 777 nm and a restricted non-LTE
analysis, i.e. spectrum synthesis was performed with non-LTE level
populations on an LTE atmospheric structure. We confirm previous studies
that suggest higher oxygen abundances in the thick disk than in the thin
disk although our preliminary results favor a smooth transition instead
of two completely separate trends, i.e. thick disk stars with
intermediate and relatively lower oxygen abundances are also found.