Winds from Hot Stars

This review deals with the winds from “normal” hot stars such as O-stars, B- and A-supergiants, and Central Stars of Planetary Nebulae with O-type spectra. The advanced diagnostic methods of stellar winds, including an assessment of the accuracy of the determinations of global stellar wind parameters (terminal velocities, mass-loss rates, wind momenta, and energies), are introduced and scaling relations as a function of stellar parameters are provided. Observational results are interpreted in the framework of the stationary, one-dimensional (1-D) theory of line-driven winds. Systematic effects caused by nonhomogeneous structures, time dependence, and deviations from spherical symmetry are discussed. The review finishes with a brief description of the role of stellar winds as extragalactic distance indicators and as tracers of the chemical composition of galaxies at high redshift.