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Photoionized features in the X-ray spectrum of Ex Hydrae

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Luna, G. J. M., Raymond, J., Brickhouse, Nancy, Mauche, Christopher W., Proga, D., Steeghs, D. (Danny), 1972- and Hoogerwerf, R.. (2010) Photoionized features in the X-ray spectrum of Ex Hydrae. Astrophysical Journal, Vol.711 (No.2). pp. 1333-1337. ISSN 0004-637X

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Official URL: http://dx.doi.org/10.1088/0004-637X/711/2/1333

Abstract

We present the first results from a long (496 ks) Chandra High Energy Transmission Grating observation of the intermediate polar EX Hydrae ( EX Hya). In addition to the narrow emission lines from the cooling post-shock gas, for the first time we have detected a broad component in some of the X-ray emission lines, namely, O VIII lambda 18.97, Mg XII lambda 8.42, Si XIV lambda 6.18, and Fe XVII lambda 16.78. The broad and narrow components have widths of similar to 1600 km s(-1) and similar to 150 km s(-1), respectively. We propose a scenario where the broad component is formed in the pre-shock accretion flow, photoionized by radiation from the post-shock flow. Because the photoionized region has to be close to the radiation source in order to produce strong photoionized emission lines from ions such as O VIII, Fe XVII, Mg XII, and Si XIV, our photoionization model constrains the height of the standing shock above the white dwarf surface. Thus, the X-ray spectrum from EX Hya manifests features of both magnetic and non-magnetic cataclysmic variables.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Cataclysmic variable stars
Journal or Publication Title:	Astrophysical Journal
Publisher:	IOP Publishing
ISSN:	0004-637X
Official Date:	10 March 2010
Volume:	Vol.711
Number:	No.2
Number of Pages:	5
Page Range:	pp. 1333-1337
Identification Number:	10.1088/0004-637X/711/2/1333
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	United States. National Aeronautics and Space Administration (NASA), United States. Dept. of Energy
Grant number:	GO7-8026X (NASA), NAS8-03060 (NASA), DE-AC52-07NA27344 (DoE)
Related URLs:	Other Repository
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URI:	http://wrap.warwick.ac.uk/id/eprint/6354