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Yasuharu Sugawara, Yoshitomo Maeda, Yohko Tsuboi, Kenji Hamaguchi, Michael Corcoran, Andy Pollock, Anthony Moffat, Peredur Williams, Sean Dougherty & Julian Pittard

The variable X-ray spectrum of theWolf-Rayet binary WR140 with Suzaku

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Open Access

Abstract

We report the preliminary results of the Suzaku observations of the W-R binaryWR140 (WC7+O5I). We executed the observations at four different epochs around periastron passage in Jan. 2009 to understand the W-R stellar wind as well as the wind-wind collision shocks. The total exposure was 210 ks. We detected hard X-ray excess in the HXD band (> 10 keV) for the first time from a W-R binary. Another notable discovery was a soft component which is less absorbed even by the dense wind. The spectra can be fitted by three different components; one is for the cool component with kT=0.1–0.6 keV, one for a dominant high-temperature component with kT ~3 keV, and one for the hardest power-law component with the photon index of ~2. As periastron approached, the column density of the high-temperature component increased, which can be explained as self-absorption by the W-R wind. The emission measure of the dominant, high-temperature component is not inversely proportional to the distance between the two stars.

To cite this article

Yasuharu Sugawara, Yoshitomo Maeda, Yohko Tsuboi, Kenji Hamaguchi, Michael Corcoran, Andy Pollock, Anthony Moffat, Peredur Williams, Sean Dougherty & Julian Pittard, «The variable X-ray spectrum of theWolf-Rayet binary WR140 with Suzaku», Bulletin de la Société Royale des Sciences de Liège [En ligne], Volume 80 - Année 2011, 724 - 728 URL : https://popups.uliege.be/0037-9565/index.php?id=3199.

About: Yasuharu Sugawara

Department of Physics, Chuo University, Japan

About: Yoshitomo Maeda

Department of High Energy Astrophysics, ISAS/JAXA

About: Yohko Tsuboi

Department of Physics, Chuo University, Japan

About: Kenji Hamaguchi

CRESST and X-ray Astrophysics Laboratory NASA/GSFC, and

About: Michael Corcoran

Department of Physics, University of Maryland

About: Andy Pollock

CRESST and X-ray Astrophysics Laboratory NASA/GSFC, and

About: Anthony Moffat

Universities Space Research Association

About: Peredur Williams

European Space Agency, XMM-Newton Science Operations Centre

About: Sean Dougherty

Département de Physique, Université de Montréal

About: Julian Pittard

Institute for Astronomy, Royal Observatory Edinburgh