Journal Article

Colliding winds in five WR+O systems of the Southern hemisphere

R. Fahed and A. F. J. Moffat

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 424, issue 3, pages 1601-1613
Published in print August 2012 | ISSN: 0035-8711
Published online August 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.20494.x
Colliding winds in five WR+O systems of the Southern hemisphere

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Abstract

We present the results of an optical spectroscopic follow-up of five WR+O systems of the Southern hemisphere that have not been studied so far for wind–wind collisions: WR 12 (WN8h), WR 21 (WN5o+O7V), WR 30 (WC6+O7.5V), WR 31 (WN4o+O8) and WR 47 (WN6o+O5). Observations were made over an entire contiguous month using the Garrison spectrograph attached to the 0.6-m Helen Sawyer Hogg telescope at Complejo Astronomico El Leoncito. We obtain improved orbital elements for these five systems and provide an estimation of the orbital inclination and shock-cone opening angle for four of them by analysing excess emission profiles with the geometrical model of Lührs. We argue that line variability in one of the stars (WR 12) might be dominated by some dynamic instabilities in the shocked plasma, making the model inappropriate in this case. A sixth star, WR 69 (WC9d+OB), was observed in the programme based on its published photometric period of 2.293 ± 0.005 d. While we found a probable spectroscopic period of 2.15 ± 0.04 d compatible with that of Marchenko et al. (1998), the period is unlikely related to orbital effects, rather to (relatively fast) rotation of the WC9d component of a much longer binary system.

Keywords: binaries: general; stars: fundamental parameters; stars: winds, outflows; stars: Wolf–Rayet

Journal Article.  6190 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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