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arXiv · 2611.07986

Mass loss in AF supergiants: At the verge of the Eddington limit and still with weak line-driven winds

Jiri Krticka·Jiri Kubat
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Abstract

We study global atmosphere models of AF supergiants. In agreement with previous studies, we found super-Eddington layers in the photospheres of these stars, which lead to density inversions. Our tests showed that the super-Eddington layers are caused by hydrogen ionization. The analysis of radial perturbations has not revealed any instability of such layers, but we show that super-Eddington layers in an optically thick environment are prone to instabilities due to nonradial perturbations. We predict the wind parameters of AF supergiants from our global wind code with a comoving-frame radiative force. Despite the existence of density inversions, the predicted mass-loss rates are significantly lower than those estimated from observations. Theoretical values approach the observational estimates only for the most luminous supergiants, which are close to the Eddington limit due to light scattering on free electrons. Part of the discrepancy between the mass-loss rates could be attributed to the influence of the clumping on the observational properties. Low mass-loss rates imply that the winds of AF supergiants may be strongly influenced by the magnetic fields, suggesting an explanation for the observed spectral variability of these stars.

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Jiri Krticka, Jiri Kubat. 2026-11-05. Mass loss in AF supergiants: At the verge of the Eddington limit and still with weak line-driven winds. https://arxiv.org/abs/2611.07986

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