Viscous radiation driven disks in fast rotating massive stars
Fecha
2022-08
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Universidad de Valparaíso
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Facultad de Ciencias
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Instituto de Fisica y Astronomia
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Magíster en Astrofísica
Resumen
Previous studies of equatorial winds from high rotating massive stars, considered angular momentum conservation, have found a dependency between stellar rotation rate (Ω) and a new type of solution: the Ω-slow solution (for Ω ≳ 0.75), characterized by winds with low terminal velocities and high densities. It is believed that this type of solution could explain the low terminal velocities from the observational results of classical Be stars, which are the fastest rotating stars among non-degenerate stars.
From the study of wind solutions of fast rotating main sequence B-type stars, considering models with winds rotating in a quasi-Keplerian way (without conser- vation of angular momentum), the main objective of this work is to obtain a wind velocity profile that reproduce the low terminal velocities of classical Be stars. For this purpose, we introduced a parameter that mimics viscosity (γvis) into the 1D nonlinear stationary differential equation of radiation driven winds (based on the m-CAK model) and we solved it using the hydrodynamic code HYDWIND.
Compared to the models where the wind rotates conserving angular momentum (γvis = 1.0), the models of B2 V and B2.5 V stars studied in this work, where their winds rotate in a quasi-Keplerian way (0.5 < γvis < 1.0), present Ω-slow solutions with low terminal velocities. When γvis −→ 0.5, the lower the terminal velocity. On the other hand, using eight different main sequence B-type stars with a given interval of Ωs, we studied the influence of γvis in the region where standard m-CAK solutions and Ω-slow solutions can co-exist, called the co-existence region. Our results show that when the wind rotates in a quasi-Keplerian way, the interval of values of Ω, corresponding to the co-existence region, is shifted to higher values of Ω.
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ESTRELLAS MULTIPLES, ROTACION DE ESTRELLAS, VIENTOS, RADIACION