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Metallicity of M dwarfs
IV. A high-precision [Fe/H] and Teff technique from high-resolution optical spectra for M dwarfs

V. Neves, X. Bonfils, N. C. Santos, X. Delfosse, T. Forveille, F. Allard, S. Udry

Abstract
Aims. In this work we develop a technique to obtain high precision determinations of both metallicity and effective temperature of M dwarfs in the optical.
Methods.
A new method is presented that makes use of the information of 4104 lines in the 530–690 nm spectral region. It consists in the measurement of pseudo equivalent widths and their correlation with established scales of [Fe/H] and Teff.
Results.
Our technique achieves a rms of 0.08 ± 0.01 for [Fe/H], 91 ± 13 K for Teff, and is valid in the (−0.85,0.26 dex), (2800, 4100 K), and (M0.0, M5.0) intervals for [Fe/H], Teff and spectral type respectively. We also calculated the RMSEV which estimates uncertainties of the order of 0.12 dex for the metallicity and of 293 K for the effective temperature. The technique has an activity limit and should only be used for stars with log LHα/Lbol< − 4.0.

Keywords
stars: atmospheres - stars: fundamental parameters - stars: late-type - stars: low-mass - methods: data analysis

Astronomy and Astrophysics
Volume 568, Number of pages A121_1
2014 August

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Instituto de Astrofísica e Ciências do Espaço Universidade do Porto Faculdade de Ciências da Universidade de Lisboa Fundação para a Ciência e a Tecnologia
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