New theoretical mass-loss rates of O and B stars

We have calculated mass-loss rates for a grid of wind models covering a wid e range of stellar parameters and have derived a mass-loss recipe for two r anges of effective temperature at either side of the bi-stability jump arou nd spectral type B1. For a large sample of O stars, it is shown that there is now good agreement between these new theoretical mass-loss rates that take multiple scatterin g into account and observations. Agreement between the observed and new theoretical wind momenta increases c onfidence in the possibility to derive distances to luminous stars in dista nt stellar systems using the Wind momentum Luminosity Relation. For the winds of the B stars there is an inconsistency in the literature be tween various mass-loss rate determinations from observations by different methods. One group of (M) over dot determinations of B stars does follow th e new theoretical relation, while another group does not. The lack of agree ment between the observed mass-loss rates derived by different methods may point to systematic errors in mass-loss determinations from observations fo r B stars. We show that our theoretical mass-loss recipe is reliable and recommend it be used in evolutionary calculations.