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Remarkable long-term changes in the small Magellanic Cloud Wolf-Rayet system HD 5980In this paper we report the remarkable changes which occured in the Small Magellanic Cloud W-R system HD5980 = AB5 between 1978 and 1991. Within this timescale, there has been a systematic enhancement (by factors of 2-10 depending on the line) in the equivalent widths of all emission lines, and a change in the relative strengths of N III, N IV, and N V lines. Currently, the W-R spectrum is more typical of a WN6 star than a WN3 or WN4, as it was originally classified. The terminal speed of the wind has diminished by approximately 600 km/s, while the system has brightened in the visual by 0.45 mag. The UV (1850 A) continuum changed by less than 0.13 mag. The change from WN3 or WN4 to WN6 is unprecedented. The system appears to be composed at least three stars: two WNs in mutual 19.266 day orbit and an O-type supergiant. We propose that the changes observed in HD 5980 are related to an increase in wind density of one (or both?) of the W-R components, where the brighter WN6 component will dominate the W-R spectrum after the change, and we speculate that this modification of the wind structure is driven by tidal interaction induced by a possible current periastron passage of the third component in the system.
Document ID
19950037141
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Koenigsberger, G.
(UNAM Mexico)
Moffat, A. F. J.
(Univ. de Montreal Montreal, QC, Canada)
St-Louis, N.
(Univ. de Montreal Montreal, QC, Canada)
Auer, L. H.
(Los Alamos National Lab. Los Alamos, NM, United States)
Drissen, L.
(Space Telescope Science Inst. Baltimore, MD, United States)
Seggewiss, W.
(Univ. Bonn Germany)
Date Acquired
August 16, 2013
Publication Date
November 20, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 436
Issue: 1
ISSN: 0004-367X
Subject Category
Astronomy
Accession Number
95A68740
Distribution Limits
Public
Copyright
Other

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