The Effective Temperature Determination

Extract

The content of my oral contribution has been reduced here to a guide to the recent litterature on the subject.

The effective temperature of a star can be obtained directly by measuring the total flux received on earth from it, and its angular diameter. In principle interferometrie methods could determine both the limb-darkening law of the stellar disk and the angular diameter of the disk. In practice, in order to obtain a decent accuracy on the angular diameter, interferometrie methods have so far borrowed the limb-darkening law from stellar atmosphere theory, in order to concentrate all the observational information on a single parameter. The total number of stellar diameters and effective temperatures obtained by this basic method remains very small (about 30 stars) and concerns exclusively giant or subgiant stars. The reader is invited to look at the following references and those therein (Di Benedetto 1993, Mozurkewich et al. 1991, Alonso et al. 1994). Smalley and Dworetsky (A&A in press) have reinvestigated the old Code et al. (1976) calibration with more recent spatial UV data, for B, A, and F stars, and have found no significant changes. The accuracy of the basic method is at the best of the order of 1.5 %, and there is a deep need for more data, and for doubling the current accuracy. Actually there is a strong effort for developping interferometry both from the ground (ESO VLTI, USNO astrometric interferometer) andfrom space (OSI project, Colavita et al. 1993; GAIA project at ESA). So there is hope for a not to far future.