Observatoire de Paris-Meudon, DASGAL, URA 335 du CNRS, F-92195 Meudon Cedex, France
2 Observatoire de Haute Provence, UPR 9049 du CNRS, F-04870 Saint Michel l'Observatoire, France
3 Dipartimento di Astronomia, v. Tiepolo 11, 34131 Trieste, Italy
4 Institut d'Astrophysique de Paris, CNRS, 98bis Bd. Arago, F-75014 Paris, France
Send offprint request to: R. Burnage
Accepted: 19 November 1998
Radial velocities have been determined for a sample of B8-F2 type stars observed by the Hipparcos satellite. Observations were obtained within the framework of an ESO key-program. Radial velocities have been measured using a cross-correlation method, the templates being a grid of synthetic spectra. The obtained precision depends on effective temperature and projected rotational velocity of the star as well as on a possible asymmetry of the correlation peak generally due to secondary components. New spectroscopic binaries have been detected from these asymmetries and the variability of the measured radial velocity. Simulations of binary and triple systems have been performed. For binaries our results have been compared with Hipparcos binary data. Adding the variable radial velocities, the minimum binary fraction has been found 60% for physical systems. Radial velocities have been determined for 581 B8-F2 stars, 159 being new. Taking into account published radial velocities, 39% south A-type stars with V magnitude lower than 7.5 have a radial velocity.
Key words: techniques: spectroscopic / stars: early- type / stars: fundamental parameters / binaries: spectroscopic
Based on observations obtained at the European Southern Observatory (ESO, La Silla, Chile) and on data from the ESA Hipparcos astrometry satellite.
Tables 7, 8 and 9 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (126.96.36.199) or via http://cdsweb.u-strasbg.fr/Abstract.html
© European Southern Observatory (ESO), 1999