Article
High-Resolution X-ray Spectroscopy reveals the Special Nature of the Wolf-Rayet Star Winds.
The Astrophysical Journal
(2012)
Abstract
We present the first high-resolution X-ray spectrum of a putatively single Wolf–Rayet (WR) star. 400 ks observations of WR 6 by the XMM-Newton telescope resulted in a superb quality high-resolution X-ray spectrum. Spectral analysis reveals that the X-rays originate far out in the stellar wind, more than 30 stellar radii from the photosphere, and thus outside the wind acceleration zone where the line-driving instability (LDI) could create shocks. The X-ray emitting plasma reaches temperatures up to 50 MK and is embedded within the unshocked, “cool” stellar wind as revealed by characteristic spectral signatures. We detect a fluorescent Fe line at ≈6.4 keV. The presence of fluorescence is consistent with a two-component medium, where the cool wind is permeated with the hot X-ray emitting plasma. The wind must have a very porous structure to allow the observed amount of X-rays to escape. We find that neither the LDI nor any alternative binary scenario can explain the data. We suggest a scenario where X-rays are produced when the fast wind rams into slow “sticky clumps” that resist acceleration. Our new data show that the X-rays in single WR star are generated by some special mechanism different from the one operating in the O-star winds.
Keywords
- High-Resolution,
- X-ray Spectroscopy,
- Special Nature,
- Wolf-Rayet Star Winds
Disciplines
Publication Date
March 10, 2012
DOI
10.1088/2041-8205/747/2/L25
Citation Information
L. M. Oskinova, K. G. Gayley, W.-R. Hamann, D. P. Huenemoerder, et al.. "High-Resolution X-ray Spectroscopy reveals the Special Nature of the Wolf-Rayet Star Winds." The Astrophysical Journal Vol. 747 (2012) ISSN: 0004-637X Available at: http://works.bepress.com/richard_ignace/42/