Effective temperatures of cool metal-poor stars derived from the analysis of 3D Balmer lines
Résumé
Balmer lines are recognized as accurate indicators of the effective temperature of late-type stars. The influence of convection on the shape of Balmer line profiles has been investigated using LTE 3D hydrodynamical model atmospheres and `classical' LTE 1D stellar atmospheres, where convection is modeled within the simplistic picture of mixing-length theory. Models and line profiles computed with the CO5BOLD and Linfor3D codes have been used to determine the effective temperatures of the Sun and three well known metal-poor stars HD84937, HD74000, and HD140283. Our 3D fit provides the best fit thus far for the solar Halpha temperature using the Barklem theory. The resulting (3D-1D) Teff biases related to the different treatment of convection in the 1D and 3D models are presented.