Metallicity of M dwarfs
IV. A high-precision [Fe/H] and T_eff 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 T_eff.
Results. Our technique achieves a rms of 0.08 ± 0.01 for [Fe/H], 91 ± 13 K for T_eff, and is valid in the (−0.85,0.26 dex), (2800, 4100 K), and (M0.0, M5.0) intervals for [Fe/H], T_eff and spectral type respectively. We also calculated the RMSE_V 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 L_Hα/L_bol< − 4.0.

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

Astronomy and Astrophysics
Volume 568, Page A121_1
August 2014

DOI: 10.1051/0004-6361/201424139
ADS Bibliographic code: 2014A%26A...568A.121N