On the determination of oxygen abundances in chromospherically active stars

T. Morel; G. Micela

doi:10.1051/0004-6361:20040370

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On the determination of oxygen abundances in chromospherically active stars

T. Morel·G. Micela

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Abstract

We discuss oxygen abundances derived from [O I] 6300 and the O I triplet in stars spanning a wide range in chromospheric activity level, and show that these two indicators yield increasingly discrepant results with higher chromospheric/coronal activity measures. While the forbidden and permitted lines give fairly consistent results for solar-type disk dwarfs, spuriously high O I triplet abundances are observed in young Hyades and Pleiades stars, as well as in individual components of RS CVn binaries (up to 1.8 dex). The distinct behaviour of the [O I]-based abundances which consistently remain near-solar suggests that this phenomenon mostly results from large departures from LTE affecting the O I triplet at high activity level that are currently unaccounted for, but also possibly from a failure to adequately model the atmospheres of K-type stars. These results suggest that some caution should be exercised when interpreting oxygen abundances in active binaries or young open cluster stars.

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T. Morel, G. Micela. 2004-05-05. On the determination of oxygen abundances in chromospherically active stars. https://doi.org/10.1051/0004-6361%3A20040370

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