Remarkable long-term changes in the small Magellanic Cloud Wolf-Rayet system HD 5980

Abstract

view Abstract Citations (35) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Remarkable Long-Term Changes in the Small Magellanic Cloud Wolf-Rayet System HD 5980 Koenigsberger, G. ; Moffat, A. F. J. ; St-Louis, N. ; Auer, L. H. ; Drissen, L. ; Seggewiss, W. Abstract In this paper we report the remarkable changes which occurred 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 ~600 km s^-1^, 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 he composed of 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. Publication: The Astrophysical Journal Pub Date: November 1994 DOI: 10.1086/174905 Bibcode: 1994ApJ...436..301K Keywords: Companion Stars; Magellanic Clouds; Stellar Spectra; Stellar Winds; Ultraviolet Emission; Wolf-Rayet Stars; Astronomical Spectroscopy; Iue; Red Shift; Astronomy; GALAXIES: MAGELLANIC CLOUDS; STARS: INDIVIDUAL HENRY DRAPER NUMBER: HD 5980; STARS: WOLF-RAYET full text sources ADS | data products SIMBAD (5) NED (1) MAST (1) INES (1)