Astron. Astrophys. 339, 858-871 (1998)

1. Introduction

The fundamental calibration of stellar parameters of solar neighborhood stars provides the most relevant empirical support to many galactic and extragalactic investigations. These include: calibrations of the HR diagram; tests of stellar evolutionary tracks; interpretation of stellar spectra; calibrations of cosmological distance indicators. For instance, the recent developments of infrared astronomy and the new observational windows opened by the Infrared Space Observatory (ISO) for wavelengths up to at least 50 µm has put stringent requirements on the accuracy of the effective temperatures, i.e. as good as 1 %, for detailed interpretations of calibrating stellar spectra related to a large number of solar neighborhood stars (van der Bliek et al. 1992). Then, it becomes of major concern to have reliable methods to determine high-precision stellar temperatures required for this purpose.

In this paper I shall be concerned with a direct approach in attempting to approximate as much as possible fundamental stellar parameters. The method suggested so far applies the empirical surface brightness technique (Wesselink 1969; Barnes et al. 1978) along with the bolometric flux measurements and relates all the derived stellar parameters to the broadband colour as the most suitable and practically unbiased sampling observable (Di Benedetto 1993). The required photometric correlations are carefully calibrated by accurate angular diameters from modern interferometry techniques and by bolometeric flux measurements placed on an updated absolute scale. The spectral range is now extended to cover the field of A-F-G-K dwarf and giant stars. The high-precision near-infrared K magnitudes available for this purpose and the Hipparcos parallaxes applied for dereddening photometric data of distant stars have notably provided the most relevant observational support to improve significantly the accuracy of final results.

© European Southern Observatory (ESO) 1998

Online publication: October 22, 1998
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