Wind structure and luminosity variations in the Wolf-Rayet/luminous blue variable HD5980

Over the past 40 years, the massive luminous blue variable/Wolf-Rayet system HD5980 in the Small Magellanic Cloud (SMC) has undergone a long-term S Doradus-type variability cycle and two brief and violent eruptions in 1993 and 1994. In this paper we analyze a collection of UV and optical spectra obt...

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Autores principales: Georgiev, Leonid, Koenigsberger, Gloria, Hillier, D. John, Morrell, Nidia Irene, Barbá, Rodolfo Héctor, Gamen, Roberto Claudio
Formato: Articulo
Lenguaje:Inglés
Publicado: 2011
Materias:
Ciencias Astronómicas
binaries: eclipsing
stars: individual (HD 5980)
stars: variables: S Doradus
stars: Wolf–Rayet
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/84382
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-84382
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
binaries: eclipsing
stars: individual (HD 5980)
stars: variables: S Doradus
stars: Wolf–Rayet
spellingShingle Ciencias Astronómicas
binaries: eclipsing
stars: individual (HD 5980)
stars: variables: S Doradus
stars: Wolf–Rayet
Georgiev, Leonid
Koenigsberger, Gloria
Hillier, D. John
Morrell, Nidia Irene
Barbá, Rodolfo Héctor
Gamen, Roberto Claudio
Wind structure and luminosity variations in the Wolf-Rayet/luminous blue variable HD5980
topic_facet Ciencias Astronómicas
binaries: eclipsing
stars: individual (HD 5980)
stars: variables: S Doradus
stars: Wolf–Rayet
description Over the past 40 years, the massive luminous blue variable/Wolf-Rayet system HD5980 in the Small Magellanic Cloud (SMC) has undergone a long-term S Doradus-type variability cycle and two brief and violent eruptions in 1993 and 1994. In this paper we analyze a collection of UV and optical spectra obtained between 1979 and 2009 and perform CMFGEN model fits to spectra of 1994, 2000, 2002, and 2009. The results are as follows: (1) the long-term S Dor-type variability is associated with changes of the hydrostatic radius; (2) the 1994 eruption involved changes in its bolometric luminosity and wind structure; (3) the emission-line strength, the wind velocity, and the continuum luminosity underwent correlated variations in the sense that a decreasing V ∞ is associated with increasing emission line and continuum levels; and (4) the spectrum of the third star in the system (Star C) is well fit by a T eff = 32K model atmosphere with SMC chemical abundances. For all epochs, the wind of the erupting star is optically thick at the sonic point and is thus driven mainly by the continuum opacity. We speculate that the wind switches between two stable regimes driven by the "hot" (during the eruption) and the "cool" (post-eruption) iron opacity bumps as defined by Lamers & Nugis and Gräfener & Hamann, and thus the wind may undergo a bi-stability jump of a different nature from that which occurs in OB stars.
format Articulo
Articulo
author Georgiev, Leonid
Koenigsberger, Gloria
Hillier, D. John
Morrell, Nidia Irene
Barbá, Rodolfo Héctor
Gamen, Roberto Claudio
author_facet Georgiev, Leonid
Koenigsberger, Gloria
Hillier, D. John
Morrell, Nidia Irene
Barbá, Rodolfo Héctor
Gamen, Roberto Claudio
author_sort Georgiev, Leonid
title Wind structure and luminosity variations in the Wolf-Rayet/luminous blue variable HD5980
title_short Wind structure and luminosity variations in the Wolf-Rayet/luminous blue variable HD5980
title_full Wind structure and luminosity variations in the Wolf-Rayet/luminous blue variable HD5980
title_fullStr Wind structure and luminosity variations in the Wolf-Rayet/luminous blue variable HD5980
title_full_unstemmed Wind structure and luminosity variations in the Wolf-Rayet/luminous blue variable HD5980
title_sort wind structure and luminosity variations in the wolf-rayet/luminous blue variable hd5980
publishDate 2011
url http://sedici.unlp.edu.ar/handle/10915/84382
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AT hillierdjohn windstructureandluminosityvariationsinthewolfrayetluminousbluevariablehd5980
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AT barbarodolfohector windstructureandluminosityvariationsinthewolfrayetluminousbluevariablehd5980
AT gamenrobertoclaudio windstructureandluminosityvariationsinthewolfrayetluminousbluevariablehd5980
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