RADIATION-DRIVEN WINDS OF HOT LUMINOUS STARS .10. THE DETERMINATION OF STELLAR MASSES, RADII AND DISTANCES FROM TERMINAL VELOCITIES AND MASS-LOSS RATES

A new, purely spectroscopic method to determine masses, radii and distances of massive, luminous hot stars is presented. This method is based on the theory of radiation-driven winds and uses terminal velocity, mass-loss rate and effective temperature as observational quantities determined from the spectrum. It is demonstrated that in situations where the distance is already known from other methods, masses can be determined from v(infinity) and T(eff) with an accuracy of +/- 25%, which is a factor of two better than the classical method using the information obtainable from the quantitative analysis of photospheric absorption lines. These masses, which agree with those obtained from the spectroscopic values of log g, are systematically somewhat smaller than masses found from evolutionary calculations. An independent determination of radii and distances is possible, if good measurements of mass-loss rates can be carried out. For two examples, zeta-Puppis and P Cygni, it is shown that in such cases radii can be determined to an accuracy of +/- 25%. This would transform into an uncertainty in distance modulus of DELTA-m(v) = +/- 0.5 mag for an individual object. The potential of this method is discussed.