Search for reference A0 dwarf stars: Masses and luminosities revisited with HIPPARCOS parallaxes

Abstract

Hipparcos data for 71 nearby dwarf A0 stars were combined with other data, in particular with high resolution spectra to establish the HR diagram in this temperature range. Almost 30% of unknown binaries were detected and discarded before establishing the cal M-L relation for bright A0 V field stars. The relationship derived for these single stars is compared to the classical diagram derived from eclipsing binaries. The scatter of the latter is examined and the role of gravity is discussed. A good agreement is found between the evolution-based surface gravity log g_ev and the value of log g_ph obtained from photometric data. Based on observations collected at the European Southern Observatory (ESO), La Silla, Chile in the framework of the Key Programme 5-004-43K and on data from the ESA Hipparcos astrometry satellite. The Tables 1-4 are also available electronically via anonymous ftp 130.79.128.5 or via http://cdsweb.u-strasbg.fr/Abstract.html