On the Role Played by Lines in Radiatively Driven Stellar Winds Depending on the Position of the Stars in the HR Diagram

The radiative force due to transfer in ultraviolet lines is always an important mechanism in hot star wind dynamics. However, it is not clear when it is the dominant mechanism and which are the noise parameters. To investigate the efficiency of purely radiative momentum/energy transfer in hot star winds and in various regions of the HR diagram, the Leroy and Lafon model was improved and put to its limits; correlations between the mass loss rate, the luminosity and other parameters and the theoretical and the observational results, looking for observed stars violating the model were compared. It is concluded that in widespread region of the HR diagram, line driven models are consistent with observations, the radiative equilibrium physics is relevant throughout the expanding atmospheres and the mass loss rate is quasilinearly correlated with the luminosity.