Research Note

Modelling convection in A star atmospheres

Bisectors and lineshapes of HD 108642

University of Vienna, Universitätsstrasse 7, 1010 Vienna, Austria e-mail: christian.stuetz@univie.ac.at

Received: 30 January 2009
Accepted: 3 July 2009

Abstract

Context. We present a code, VeDyn, for modelling envelopes and atmospheres of A to F stars focusing on accurate treatment of convective processes.

Aims. VeDyn implements a highly sophisticated non-local convection model but is fast and can be used in practical astrophysical applications.

Methods. We developed the HME envelope solver for this convection model to consistently model the envelope together with the stellar atmosphere. The synthesis code SynthV was extended to account for the resulting velocity structure. Finally, we tested our approach on atomic line bisectors.

Results. It is shown that our synthetic line bisectors of HD 108642 bend towards the blue and are of a magnitude comparable to the observed ones.

Conclusions. Even though this approach of modelling convection requires the solution of a coupled system of nonlinear differential equations, it is fast enough to be applicable to many of the investigation techniques relying on model atmospheres.