Astronomy and Astrophysics – Astronomy
Scientific paper
May 2003
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003apj...588.1072b&link_type=abstract
The Astrophysical Journal, Volume 588, Issue 2, pp. 1072-1081.
Astronomy and Astrophysics
Astronomy
15
Stars: Abundances, Stars: Individual (Hd 122563), Stars: Population Ii
Scientific paper
HD 122563 is a well-known bright (V=6.2) halo giant of low metallicity ([Fe/H]~-2.7). We have observed HD 122563 for infrared OH lines at 1.5-1.7 μm in the H band with the NIRSPEC high-resolution spectrograph at the 10 m Keck Telescope. Optical spectra were obtained with the UVES spectrograph at the 8 m VLT UT2 telescope at ESO (Paranal) and the FEROS spectrograph at ESO (La Silla). Based on the optical high-resolution data, a detailed analysis has been carried out, and data on the forbidden [O I] 6300 Å line, unblended by telluric or sky lines, was obtained with the FEROS spectrograph. Signal-to-noise ratios of 200-400 were obtained at resolutions of 37,000 in the H band and 45,000 in the optical. For the analysis we have adopted a photometric effective temperature Teff=4600 K. Two values for the gravity were adopted: a value deduced from ionization equilibrium, logg=1.1, with corresponding metallicity [Fe/H]=-2.8 and microturbulence velocity vt=2.0 km s-1; and logg=1.5, derived from the Hipparcos parallax, implying [Fe/H]=-2.71 and vt=2.0 km s-1. The forbidden [O I] 6300 Å and the permitted O I 7771 Å lines give O/Fe ratios essentially insensitive to model parameter variations, whereas the oxygen abundances from OH lines are sensitive to gravity, giving [O/Fe]=+0.9 and +0.7, respectively, for logg=1.1 and 1.5. We derive the following oxygen abundances: for model 1, [O/Fe]=+0.6, +1.1, and +0.9; and for model 2, [O/Fe]=+0.6, +1.1, and +0.7, based on the [O I] 6300 Å, O I 7771 Å, and IR OH 1.6 μm lines, respectively. The different oxygen abundance indicators give different oxygen abundances, illustrating the problem of oxygen abundance derivation in metal-poor giants. This is important because the age of globular clusters and the production of Li, Be, and B from spallation of C, N, and O atoms in the early Galaxy depend on the oxygen abundance adopted for the metal-poor stars.
Observations carried out with the Keck Telescope, Mauna Kea, Hawaii, within the Gemini-Keck agreement, the Very Large Telescope at the European Southern Observatory (ESO), Paranal, Chile, and the 1.5 m ESO telescope at ESO, La Silla, Chile.
Barbuy Beatriz
Bonifacio Piercarlo
Cayrel Roger
Damineli Augusto
Depagne Éric
No associations
LandOfFree
Oxygen Abundance in the Template Halo Giant HD 122563 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Oxygen Abundance in the Template Halo Giant HD 122563, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Oxygen Abundance in the Template Halo Giant HD 122563 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1371428