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

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 -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.