Metallicity of M dwarfs. IV. A high-precision [Fe/H] and Teff technique from high-resolution optical spectra for M dwarfs
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. Based on observations made with the HARPS instrument on the ESO 3.6 m telescope at La Silla Observatory under programme ID 072.C-0488(E)Our method is available online at http://www.astro.up.pt/resources/mcalTables 1, 2, 4, 8 are available in electronic form at http://www.aanda.org
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