A&A 503, 973–984 (2009) Astronomy DOI: 10.1051/0004-6361/200912083 & c ESO 2009 Astrophysics Atmospheric velocity fields in tepid main sequence stars, J. D. Landstreet1,2, F. Kupka3,6,H.A.Ford2,4,5,T.Officer2,T.A.A.Sigut2, J. Silaj2, S. Strasser2, and A. Townshend2 1 Armagh Observatory, College Hill, Armagh BT61 9DG, Northern Ireland 2 Department of Physics & Astronomy, University of Western Ontario, London, ON N6A 3K7, Canada e-mail:
[email protected] 3 Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85748 Garching, Germany 4 Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia 5 Australia Telescope National Facility, CSIRO, Epping, NSW 1710, Australia 6 Observatoire de Paris, LESIA, CNRS UMR 8109, 92195, Meudon, France Received 16 March 2009 / Accepted 11 June 2009 ABSTRACT −1 Context. The line profiles of the stars with ve sin i below a few km s can reveal direct signatures of local velocity fields such as convection in stellar atmospheres. This effect is well established in cool main sequence stars, and has been detected and studied in three A stars. Aims. This paper reports observations of main sequence B, A and F stars (1) to identify additional stars with sufficiently low values of ve sin i to search for spectral line profile signatures of local velocity fields and (2) to explore how the signatures of the local velocity fields in the atmosphere depend on stellar parameters such as effective temperature and peculiarity type. Methods. We have carried out a spectroscopic survey of B and A stars of low ve sin i at high resolution.