ICATE   21876
INSTITUTO DE CIENCIAS ASTRONOMICAS, DE LA TIERRA Y DEL ESPACIO
Unidad Ejecutora - UE
artículos
Título:
A ~ 40 Year Variability Cycle in the Luminous Blue Variable/Wolf-Rayet Binary System HD 5980?
Autor/es:
KOENIGSBERGER, G.; GEORGIEV, L.; HILLIER, D.J.; MORRELL, N.I.; BARBÁ, R.H.; GAMEN, R.C.
Revista:
ASTRONOMICAL JOURNAL
Editorial:
IOP PUBLISHING LTD
Referencias:
Año: 2010 vol. 139 p. 2600 - 2611
ISSN:
0004-6256
Resumen:
The massive Wolf-Rayet stellar system HD 5980 in the Small Magellanic
Cloud entered a sudden and brief ~ 1-3 mag eruptive state in the
mid-1990s. The cause of the instability is not yet understood, but
mechanisms similar to those in luminous blue variables are suspected.
Using a previously unreported set of spectroscopic data obtained in
1955-1967 and recently acquired optical and HST/STIS spectra, we find
that (1) the brief eruptions of 1993 and 1994 occurred at the beginning
of an extended (~ decades) high state of activity characterized by large
emission-line intensities; (2) the level of activity is currently
subsiding; and (3) another strong emission-line episode appears to have
occurred between 1960 and 1965, suggesting the possibility that the
long-term cyclical variability may be recurrent on a ~ 40 year
timescale. These characteristics suggest the possible classification of
HD 5980 as an S Doradus-type variable. The effects due to binary
interactions in the system are discussed, and we tentatively suggest
that the short duration and relatively hot spectral type (WN11/B1.5I)
observed during maximum in the visual light curve may be attributed to
these interactions.