Near-IR features in late type stars: their relation with stellar atmosphere parameters
Open Access
- 1 July 1989
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 239 (2) , 325-345
- https://doi.org/10.1093/mnras/239.2.325
Abstract
CCD spectroscopic observations for a sample of 106 late type stars plus three galactic globular clusters in the near-IR [λλ 7900–9100 Å) are presented. The most prominent features in that spectral region, the IR Ca II triplet (λλ 8498, 8542, 8662 Å) and the Mg I line at λ 8807 Å, are measured and their dependence on the stellar atmosphere parameters (surface gravity, effective temperature and metal content) is analysed. Complementary to what is found in previous studies, the Ca II triplet strength shows biparametrical behaviour with surface gravity and metal abundance. The IR Mg I line strength is also biparametric, depending mainly on metal abundance and effective temperature. Principal component analysis techniques allow the prediction of the metal abundance and surface gravity as a function of three observables: the IR Ca II triplet strength, the strength of the IR Mg I line and the (R–I) colour.Keywords
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