Small-scale inhomogeneities and their impact on observed mass-loss rates of radiation-driven winds

• Applicant: Privatdozent Dr. Joachim Puls
• Subject Area: Astrophysics and Astronomy
• Term: from 2011 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 179960930

The mass-loss rate is a key parameter of hot, massive stars. Large reductions of O-star mass-loss rates currently in use have been suggested, by an order of magnitude or even more, as due to the effects of wind inhomogeneities (clumping). If confirmed, such low rates would have enormous implications for massive star evolution and feedback, and thereby also for the vast number of astrophysical applications relying on evolutionary predictions.However, both atmospheric modeling and spectral synthesis accounting for the effects of wind clumping are still in their infancies, and results stemming from current models have recently been challenged by different groups, including our own. We suggest to perform a multiwavelength study for a large sample of O-stars of different chemical compositions, by using new and significantly improved methods to model the structured wind and the line formation within the entire atmosphere. With this project we will investigate apparent conflicts between observations and theory, and provide a consistent and unique view of observed mass-loss rates in the present day Universe.Moreover, our new models will be used for investigating the role of wind clumping in the predictions of ionizing fluxes from hot, massive stars, for deriving accurate surface abundances, and for cutting edge extragalactic stellar astronomy even beyond the Local Group.

• DFG Programme: Research Grants