Effective temperatures of cool metal-poor stars derived from the analysis of 3D Balmer lines

Natalie Behara (1, 2, 3) , Hans-Günter Ludwig (1, 2, 3) , Matthias Steffen (4) , Piercarlo Bonifacio (1, 2, 3, 5)

1 CIFIST - Cosmological Impact of the First Stars
2 GEPI - Galaxies, Etoiles, Physique, Instrumentation
3 Physique stellaire et galactique
4 AIP - Astrophysikalisches Institut Potsdam
5 Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Trieste, Italy

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.

Domaines: Astrophysique [astro-ph]

Natalie Behara, Hans-Günter Ludwig, Matthias Steffen, Piercarlo Bonifacio. Effective temperatures of cool metal-poor stars derived from the analysis of 3D Balmer lines. 15th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun, Jul 2008, St. Andrews (Scotland), United Kingdom. pp.784-787, ⟨10.1063/1.3099233⟩. ⟨hal-03744062⟩