Metallicity of M dwarfs: the link to exoplanets

The determination of the stellar parameters of M dwarfs is of prime importance in the fields of galactic, stellar and planetary astronomy. M stars are the least studied galactic component regarding their fundamental parameters. Yet, they are the most numerous stars in the galaxy and contribute to most of its total (baryonic) mass. In particular, we are interested in their metallicity in order to study the star-planet connection and to refine the planetary parameters. As a preliminary result we present a test of the metallicity calibrations of Bonfils et al. (2005), Johnson & Apps (2009), and Schlaufman & Laughlin (2010) using a new sample of 17 binaries with precise V band photometry