A spectroscopic study of southern (candidate) γ Doradus stars^*

II. Detailed abundance analysis and fundamental parameters

¹ Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
² School of Physics A28, University of Sydney, 2006 NSW, Australia e-mail: bruntt@physics.usyd.edu.au
³ Royal Observatory of Belgium, Ringlaan 3, 1180 Brussel, Belgium e-mail: peter@oma.be
⁴ Katholieke Universiteit Leuven, Celestijnenlaan 200B, 3001 Leuven, Belgium e-mail: conny@ster.kuleuven.ac.be
⁵ Department of Astrophysics, Radboud University Nijmegen, 6500 GL Nijmegen, The Netherlands

Received: 21 August 2007
Accepted: 23 October 2007

Abstract

Context.The γ Doradus stars are a recent class of variable main sequence F-type stars located on the red edge of the Cepheid instability strip. They pulsate in gravity modes, and this makes them particularly interesting for detailed asteroseismic analysis, which can provide fundamental knowledge of properties near the convective cores of intermediate-mass main sequence stars.

Aims.To improve current understanding of γ Dor stars through theoretical modelling, additional constraints are needed. Our aim is to estimate the fundamental atmospheric parameters and determine the chemical composition of these stars. Detailed analyses of single stars have previously suggested links to Am and λ Boo stars, so we wish to explore this interesting connection between chemical peculiarity and pulsation.

Methods.We analysed a sample of γ Dor stars for the first time, including nine bona fide and three candidate members of the class. We determined the fundamental atmospheric parameters and compared the abundance pattern with other A-type stars. We used the semi-automatic software package VWA for the analysis. This code relies on the calculation of synthetic spectra and thus takes line-blending into account. This is important because of the fast rotation in some of the sample stars, and we made a thorough analysis of how VWA performs when increasing . We obtained good results in agreement with previously derived fundamental parameters and abundances in a few selected reference stars with properties similar to the γ Dor stars.

Results.We find that the abundance pattern in the γ Dor stars is not distinct from the constant A- and F-type stars we analysed.