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Unusual 2001 periastron passage in the colliding-wind binary WR 140 (WC7pd+O4-5)

Published online by Cambridge University Press:  26 May 2016

Sergey V. Marchenko
Affiliation:
Department of Physics and Astronomy, Western Kentucky University, 1 Big Red Way, Bowling Green, KY 42101-3576, USA
Anthony F.J. Moffat
Affiliation:
Département de physique, Université de Montréal, C.P. 6128, Succ. Centre-Ville, QC H3C 3J7, Canada
Kiril P. Panov
Affiliation:
Institute of Astronomy, Bulgarian Academy of Sciences, Sofia, Bulgaria
Wilhelm Seggewiss
Affiliation:
Sternwarte der Universität Bonn, Auf dem Hügel, D-53121 Bonn, BRD
Victor G. Zubko
Affiliation:
NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA

Abstract

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The massive, long-period and highly-eccentric (P = 2899 d, e = 0.88), colliding-wind binary WR 140 (WC7pd+O4-5) may be regarded as a clock-work for its predictable, repeatable IR outbursts related to dust formation right after each periastron passage. However, the 2001 periastron passage broke this monotonic trend. Our UBV photometry, completely covering the past nine years, shows a series of quasi-regular fadings starting ~ 2 months after periastron passage (Φ ≃ 0.02-0.05). Preliminary analysis points to dust as a probable cause of the eclipse-like behavior of the system, while the oscillating pattern hints towards instabilities in the wind-wind collision zone. At the same time, contemporaneous spectroscopy shows nothing unusual aside of the strong, but short-lived signs of wind-wind interaction (Φ ≃ 0.99-1.02).

Type
Part 1. Atmospheres of Massive Stars
Copyright
Copyright © Astronomical Society of the Pacific 2003 

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