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J. P. Fulbright (UCO/Lick Observatory)
The oxygen abundances of metal-poor late-type stars can be obtained by one four methods: 1) the [O I] forbidden lines at 6300 and 6363 Å, 2) the O I triplet at 7774 Å, 3) OH lines at 3100-3150 Å, and 4) IR CO and OH bands. Each of these methods have their strengths and weaknesses, and finding common agreement between the methods has sometimes been elusive.
Recently two groups (Israelian et al, 1998, ApJ, 507, 805 and Boesgaard et al, 1999, AJ, 117, 492) have presented results from the UV OH lines and the O I triplet that suggest that the [O/Fe]-ratio continues to increase as [Fe/H] decreases. This differs from the 'traditional' result that held that [O/Fe] plateaus at ~+0.5 as [Fe/H] decreases. Conversely, Fulbright and Kraft (AJ, July 1999) show that in two very metal-poor stars the [O I] 6300 Åline gives abundances ~0.5 dex lower than obtained in the above studies.
In this talk, I hope to discuss these papers and speculate on potental causes to the discrepency.
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