HIGH-RESOLUTION X-RAY SPECTROSCOPY REVEALS THE SPECIAL NATURE OF WOLF-RAYET STAR WINDS

L. M Oskinova; W.-R Hamann; K. G Gayley; D. P Huenemoerder; R Ignace; A. M. T Pollock

doi:10.1088/2041-8205/747/2/L25

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HIGH-RESOLUTION X-RAY SPECTROSCOPY REVEALS THE SPECIAL NATURE OF WOLF-RAYET STAR WINDS

Journal article

Open access

Peer reviewed

HIGH-RESOLUTION X-RAY SPECTROSCOPY REVEALS THE SPECIAL NATURE OF WOLF-RAYET STAR WINDS

L. M Oskinova, W.-R Hamann, K. G Gayley, D. P Huenemoerder, R Ignace and A. M. T Pollock

Astrophysical journal. Letters, Vol.747(2), pp.1-6

03/10/2012

DOI: 10.1088/2041-8205/747/2/L25

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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 Almost-Equal-To 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.

ACCELERATION

ASTROPHYSICS

ASTROPHYSICS, COSMOLOGY AND ASTRONOMY

FLUORESCENCE

GAMMA ASTRONOMY

HOT PLASMA

KEV RANGE

PHOTOSPHERE

POROUS MATERIALS

RESOLUTION

STELLAR WINDS

TELESCOPE COUNTERS

WOLF-RAYET STARS

X RADIATION

X-RAY SPECTRA

X-RAY SPECTROSCOPY

Details

Title: Subtitle: HIGH-RESOLUTION X-RAY SPECTROSCOPY REVEALS THE SPECIAL NATURE OF WOLF-RAYET STAR WINDS
Creators: L. M Oskinova - Institute for Physics and Astronomy, University Potsdam, 14476 Potsdam, Germany
W.-R Hamann - Institute for Physics and Astronomy, University Potsdam, 14476 Potsdam, Germany
K. G Gayley - University of Iowa
D. P Huenemoerder - Massachusetts Institute of Technology
R Ignace - East Tennessee State University
A. M. T Pollock - European Space Agency
Resource Type: Journal article
Publication Details: Astrophysical journal. Letters, Vol.747(2), pp.1-6
DOI: 10.1088/2041-8205/747/2/L25
ISSN: 2041-8205
eISSN: 2041-8213
Publisher: The American Astronomical Society
Language: English
Date published: 03/10/2012
Academic Unit: Physics and Astronomy
Record Identifier: 9984199818502771

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