Shock-heated radiation-driven outflows as a solution to the weak-wind problem of late O-type stars

Context. Radiation-driven mass loss is key to our understanding of massive-star evolution. However, for low-luminosity O-type stars there are big discrepancies between theoretically predicted and empirically derived mass-loss rates (called the weak-wind problem). Aims. We compute radiation-line-driven wind models a typical star determine its temperature structure corresponding impact on ultra-violet (UV) line formation. Methods. carried out hydrodynamic simulations line-deshadowing instability (LDI) in Galaxy. Subsequently, we used this LDI model as input short-characteristics radiative transfer code synthetic UV profiles. Results. find that line-driven weak significantly shock heated high temperatures unable cool down effciently. This results complex where more than half volume has higher stellar effective temperature. Therefore, substantial portion will be ionised, resulting reduction opacity therefore weaker profiles given rate. Quantifying this, from unsaturated lines could underestimated by factor 10 100 if high-temperature gas not properly taken into account spectroscopic analysis. offers tentative basic explanation problem: winds really expected, but rather large their much hotter