Artículo
Wind structure and luminosity variations in the Wolf-Rayet/Luminous Blue Variable HD 5980
Georgiev, Leonid; Koenigsberger, Gloria; Hillier, D. John; Morrell, Nidia; Barba, Rodolfo Hector
; Gamen, Roberto Claudio
![Icon](/themes/CONICETDigital/images/conicet.png)
![Icon](/themes/CONICETDigital/images/conicet.png)
Fecha de publicación:
12/2011
Editorial:
Iop Publishing
Revista:
Astronomical Journal
ISSN:
0004-6256
Idioma:
Inglés
Tipo de recurso:
Artículo publicado
Clasificación temática:
Resumen
Over the past 40 years, the massive luminous blue variable/Wolf-Rayet system HD 5980 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 = 32 K 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.
Palabras clave:
Binaries
,
Variable Stars
,
Wolf-Rayet Stars
,
Eclipsing Stars
Archivos asociados
Licencia
Identificadores
Colecciones
Articulos(IALP)
Articulos de INST.DE ASTROFISICA LA PLATA
Articulos de INST.DE ASTROFISICA LA PLATA
Articulos(ICATE)
Articulos de INST.D/CS ASTRONOMICAS D/LA TIERRA Y DEL ESPACIO
Articulos de INST.D/CS ASTRONOMICAS D/LA TIERRA Y DEL ESPACIO
Citación
Georgiev, Leonid; Koenigsberger, Gloria; Hillier, D. John; Morrell, Nidia; Barba, Rodolfo Hector; et al.; Wind structure and luminosity variations in the Wolf-Rayet/Luminous Blue Variable HD 5980; Iop Publishing; Astronomical Journal; 142; 6; 12-2011; 191-210
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