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 veloc...

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Detalles Bibliográficos
Autores principales: Venero, Roberto Oscar José, Cidale, Lydia Sonia, Ringuelet, Adela Emilia
Formato: Articulo
Lenguaje:Inglés
Publicado: 2002
Materias:
Ciencias Astronómicas
Line: formation
Radiative transfer
Stars: atmospheres
Stars: early-type
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/84900
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-84900
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Astronómicas
Line: formation
Radiative transfer
Stars: atmospheres
Stars: early-type
spellingShingle Ciencias Astronómicas
Line: formation
Radiative transfer
Stars: atmospheres
Stars: early-type
Venero, Roberto Oscar José
Cidale, Lydia Sonia
Ringuelet, Adela Emilia
Constraints on the wind structure of OB stars from theoretical He II lines
topic_facet Ciencias Astronómicas
Line: formation
Radiative transfer
Stars: atmospheres
Stars: early-type
description 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 Feautrier's 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: 1. The shape of the profiles is determined by the velocity gradient at the base of the wind whenever a positive temperature gradient occurs. 2. In O-type stars, the emission-line intensity depends quite sensitively on log g, in agreement with the Walborn luminosity criterion. 3. In addition, we are able to produce emission and absorption profiles that are in qualitative agreement with those observed in O and B stars. 4. We also confirm the previous Cidale & Ringuelet and Venero, Cidale, & Ringuelet results that showed that a warm, extended, and rapidly expanding atmosphere is sufficient to give rise to emission components in the line profiles.
format Articulo
Articulo
author Venero, Roberto Oscar José
Cidale, Lydia Sonia
Ringuelet, Adela Emilia
author_facet Venero, Roberto Oscar José
Cidale, Lydia Sonia
Ringuelet, Adela Emilia
author_sort Venero, Roberto Oscar José
title Constraints on the wind structure of OB stars from theoretical He II lines
title_short Constraints on the wind structure of OB stars from theoretical He II lines
title_full Constraints on the wind structure of OB stars from theoretical He II lines
title_fullStr Constraints on the wind structure of OB stars from theoretical He II lines
title_full_unstemmed Constraints on the wind structure of OB stars from theoretical He II lines
title_sort constraints on the wind structure of ob stars from theoretical he ii lines
publishDate 2002
url http://sedici.unlp.edu.ar/handle/10915/84900
work_keys_str_mv AT venerorobertooscarjose constraintsonthewindstructureofobstarsfromtheoreticalheiilines
AT cidalelydiasonia constraintsonthewindstructureofobstarsfromtheoreticalheiilines
AT ringueletadelaemilia constraintsonthewindstructureofobstarsfromtheoreticalheiilines
bdutipo_str Repositorios
_version_ 1764820488692957188

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