NLTE models of line-driven stellar winds III. Influence of X-ray radiation on wind structure of O stars - Astrophysics > Solar and Stellar AstrophysicsReport as inadecuate




NLTE models of line-driven stellar winds III. Influence of X-ray radiation on wind structure of O stars - Astrophysics > Solar and Stellar Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We study the influence of X-rays on the wind structure of selected O stars.For this purpose we use our non-local thermodynamic equilibrium NLTE windcode with inclusion of additional artificial source of X-rays, assumed tooriginate in the wind shocks.We show that the influence of shock X-ray emission on wind mass-loss rate isrelatively small. Wind terminal velocity may be slightly influenced by thepresence of strong X-ray sources, especially for stars cooler than Teff < 35000 K.We discuss the origin of the Lx-L \sim 10^-7 relation. For stars with thickwind this relation can be explained assuming that the cooling time depends onwind density. Stars with optically thin winds exhibiting the -weak windproblem- display enhanced X-ray emission which may be connected with largeshock cooling length. We propose that this effect can explain the -weak windproblem-.Inclusion of X-rays leads to a better agreement of the model ionizationstructure with observations. However, we do not found any significant influenceof X-rays on Pv ionization fraction implying that the presence of X-rays cannotexplain the Pv problem.We study the implications of modified ionization equilibrium due to shockemission on the line transfer in the X-ray region. We conclude that the X-rayline profiles of helium-like ions may be affected by the line absorption withinthe cool wind.



Author: Jiri Krticka, Jiri Kubat

Source: https://arxiv.org/



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