The new Toulouse-Geneva stellar evolution code including radiative accelerations of heavy elements

¹ Université de Toulouse, UPS-OMP, IRAP, Toulouse, France
e-mail: sylvie.theado@ast.obs-mip.fr
² CNRS, IRAP, 14 avenue Édouard Belin, 31400 Toulouse, France
³ LUTH, Observatoire de Paris, CNRS, Université Paris Diderot, 5 place Jules Janssen, 92190 Meudon, France
e-mail: georges.alecian@obspm.fr
⁴ Département de Physique et d’Astronomie, Université de Moncton, Moncton, NB, E1A 3E9, Canada
e-mail: francis.leblanc@umoncton.ca

Received: 15 May 2012
Accepted: 16 August 2012

Abstract

Context. Atomic diffusion has been recognized as an important process that has to be considered in any computations of stellar models. In solar-type and cooler stars, this process is dominated by gravitational settling, which is now included in most stellar evolution codes. In hotter stars, radiative accelerations compete with gravity and become the dominant ingredient in the diffusion flux for most heavy elements. Introducing radiative accelerations into the computations of stellar models modifies the internal element distribution and may have major consequences on the stellar structure. Coupling these processes with hydrodynamical stellar motions has important consequences that need to be investigated in detail.

Aims. We aim to include the computations of radiative accelerations in a stellar evolution code (here the TGEC code) using a simplified method (SVP) so that it may be coupled with sophisticated macroscopic motions. We also compare the results with those of the Montreal code in specific cases for validation and study the consequences of these coupled processes on accurate models of A- and early-type stars.

Methods. We implemented radiative accelerations computations into the Toulouse-Geneva stellar evolution code following the semi-analytical prescription proposed by Alecian and LeBlanc. This allows more rapid computations than the full description used in the Montreal code.

Results. We present results for A-type stellar models computed with this updated version of TGEC and compare them with similar published models obtained with the Montreal evolution code. We discuss the consequences for the coupling with macroscopic motions, including thermohaline convection.