Emilio G. Marfil
  D. Montes, H. M. Tabernero, F. J. Lazaro Barrasa, J. A. Caballero, J. I. Gonzalez Hernandez and the CARMENES Consortium
  
  Universidad Complutense de Madrid
  
  Twinkle, twinkle, little star: Unravelling the stellar atmospheric parameters of CARMENES GTO M dwarfs using the spectral synthesis technique
  
  POSTER
  
  We focus on our very first results in connection with the stellar atmospheric parameter determinations (Teff, log g, [M/H]) of M-type dwarfs observed with CARMENES under its GTO programme by means of the spectral synthesis technique. We also describe our three-step approach to the problem: first, the careful selection of spectral ranges around iron and titanium atomic lines and molecular bands in three reference M-type stars: GX And (M1.0 V), Luyten's star (M3.5 V), and Teegarden's star (M7.0 V); second, the use of BT-Settl stellar model atmospheres, the radiative transfer code Turbospectrum and line data from the VALD3 database to obtain a grid of synthetic spectra to be compared with the CARMENES spectra; and finally, the Markov Chain Monte Carlo process implemented in SteParSyn code designed to derive the probability distribution functions of the stellar atmospheric parameters.