Jorge Meléndez et al. 2001 ApJ 556 858 doi:10.1086/321624
Jorge Meléndez1,3, Beatriz Barbuy1 and François Spite2
Show affiliationsInfrared OH lines at 1.55-1.56 μm in the H band were obtained with the Phoenix high-resolution spectrograph at the 2.1 m telescope of the Kitt Peak National Observatory for a sample of 14 metal-poor stars. Detailed analyses of the sample stars have been carried out, deriving stellar parameters based on two methods: (a) spectroscopic parameters and (b) infrared flux method (IRFM) effective temperatures, trigonometric gravities, and metallicities from Fe II lines. The Fe I lines present in the H-band region observed were well fitted by the stellar parameters within Δ[Fe/H] ≤ 0.15 dex. The oxygen abundances were derived from fits of spectrum synthesis calculations to the infrared OH lines. CO lines in the H and K bands were obtained for a subsample in order to determine their carbon abundances. Adopting the spectroscopic parameters, a mean oxygen-to-iron ratio of [O/Fe] ≈ 0.52 is obtained, whereas using the IRFM temperatures, Hipparcos gravities, and [Fe II/H], [O/Fe] ≈ 0.25 is found. A mean of the two methods gives a final value of [O/Fe] ≈ 0.4 for the metallicity range -2.2 < [Fe/H] < -1.2 of the sample metal-poor stars.
infrared: stars; stars: abundances; stars: late-type; stars: Population II
Issue 2 (2001 August 1)
Received 2000 July 11, accepted for publication 2001 April 9
Jorge Meléndez et al. 2001 ApJ 556 858
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