R. O. Venero

Constraints on the Wind Structure of OB Stars from Theoretical He II Lines

Theoretical profiles of He II lines in OB stars with an expanding, spherically symmetric atmosphere are computed. The extended atmospheric model is formed by a classical photosphere, characterized by the effective temperature and the surface gravity, and superimposed layers that have different velocity and temperature structure. We solve rigorously the radiative transfer equation, simultaneously with the statistical equilibrium equations for multilevel atoms, by making use of Feautriers method in the comoving frame. We discuss the influence on the He II lines of the hydrodynamic and thermodynamic structure of the atmosphere, paying special attention to those configurations that give rise to emission lines. The main conclusions of our work can be summarized as follows:

THE WIND OF ROTATING B SUPERGIANTS. I. DOMAINS OF SLOW AND FAST SOLUTION REGIMES

Fil: Venero, Roberto Oscar Jose. Universidad Nacional de la Plata. Facultad de Ciencias Astronomicas y Geofisicas; Argentina

Wind properties of variable B supergiants. Evidence of pulsations connected with mass-loss episodes

Fil: Haucke, Maximiliano. Universidad Nacional de La Plata. Facultad de Ciencias Astronomicas y Geofisicas; Argentina

Delta-slow solution to explain B supergiant stars' winds

A new radiation-driven wind solution called δ-slow was found by Cure et al . ( 2011 ) and it predicts a mass-loss rate and terminal velocity slower than the fast solution (m-CAK, Pauldrach et al . 1986 ). In this work, we present our first synthetic spectra based on the δ-slow solution for the wind of B supergiant (BSG) stars. We use the output of our hydrodynamical code HYDWIND as input in the radiative transport code FASTWIND (Puls et al . 2005 ). In order to obtain stellar and wind parameters, we try to reproduce the observed Hα, Hβ, Hγ, Hδ, He i 4471, He i 6678 and He ii 4686 lines. The synthetic profiles obtained with the new hydrodynamical solutions are in good agreement with the observations and could give us clues about the parameters involved in the radiation force.

Pulsations as a mass-loss trigger in evolved hot stars

During the post-main sequence evolution massive stars pass through several short-lived phases, in which they experience enhanced mass loss in the form of clumped winds and mass ejection events of unclear origin. The discovery that stars populating the blue, luminous part of the Hertzsprung-Russell diagram can pulsate hence suggests that stellar pulsations might influence or trigger enhanced mass loss and eruptions. We present recent results for two objects in different phases: a B[e] star at the end of the main sequence and a B-type supergiant.