Suzaku monitoring of the Wolf–Rayet binary WR 140 around periastron passage: An approach for quantifying the wind parameters
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- Yasuharu Sugawara
- 1Department of Physics, Faculty of Science & Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo, Tokyo 112-8551, Japan
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- Yoshitomo Maeda
- 2Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 229-8510, Japan
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- Yohko Tsuboi
- 1Department of Physics, Faculty of Science & Engineering, Chuo University, 1-13-27 Kasuga, Bunkyo, Tokyo 112-8551, Japan
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- Kenji Hamaguchi
- 4CRESST and X-ray Astrophysics Laboratory NASA/GSFC, Greenbelt, MD 20771, USA
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- Michael Corcoran
- 4CRESST and X-ray Astrophysics Laboratory NASA/GSFC, Greenbelt, MD 20771, USA
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- Andy M. T. Pollock
- 7European Space Agency, XMM-Newton Science Operations Centre, European Space Astronomy Centre, Apartado 78, Villanueva de la Cañada, 28691 Madrid, Spain
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- Anthony F. J. Moffat
- 9Département de Physique, Université de Montréal, Succursale Centre-Ville, Montréal, QC H3C 3J7, and Centre de Recherche en Astrophysique du Québec, Canada
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- Peredur M. Williams
- 10Institute for Astronomy, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
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- Sean Dougherty
- 11National Research Council of Canada, DRAO, Penticton 717 White Lake Road, Penticton, British Columbia V2A 6J9, Canada
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- Julian Pittard
- 12School of Physics and Astronomy, The University of Leeds, Leeds LS2 9JT, UK
抄録
<jats:title>Abstract</jats:title> <jats:p>Suzaku observations of the Wolf–Rayet (W–R) binary WR 140 (WC7pd+O5.5fc) were made at four different times around periastron passage in 2009 January. The spectra changed in shape and flux with the phase. As periastron approached, the column density of the low-energy absorption increased, which indicates that the emission from the wind–wind collision plasma was absorbed by the dense W–R wind. The spectra can be mostly fitted with two different components: a warm component with kBT = 0.3–0.6 keV and a dominant hot component with kBT ∼ 3 keV. The emission measure of the dominant, hot component is not inversely proportional to the distance between the two stars. This can be explained by the O star wind colliding before it has reached its terminal velocity, leading to a reduction in its wind momentum flux. At phases closer to periastron, we discovered a cool plasma component in a recombining phase, which is less absorbed. This component may be a relic of the wind–wind collision plasma, which was cooled down by radiation, and may represent a transitional stage in dust formation.</jats:p>
収録刊行物
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- Publications of the Astronomical Society of Japan
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Publications of the Astronomical Society of Japan 67 (6), 121-, 2015-11-04
Oxford University Press (OUP)