PHOTOIONIZED FEATURES IN THE X-RAY SPECTRUM OF EX HYDRAE

Journal Article · Wed Mar 10 04:00:00 EST 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/711/2/1333· OSTI ID:21394257

Luna, G J. M.; Raymond, J C; Brickhouse, N S ^[1]; Mauche, C W ^[2]; Proga, D ^[3]; Steeghs, D ^[4]; Hoogerwerf, R ^[5]

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1. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
2. Lawrence Livermore National Laboratory, L-473, 7000 East Avenue, Livermore, CA 94550 (United States)
3. Department of Physics and Astronomy, University of Nevada, 4505 South Maryland Parkway, Box 454002, Las Vegas, NV 89154-4002 (United States)
4. Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)
5. Interactive Supercomputing, Inc., 135 Beaver Street, Waltham, MA 02452 (United States)

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 lambda18.97, Mg XII lambda8.42, Si XIV lambda6.18, and Fe XVII lambda16.78. The broad and narrow components have widths of {approx}1600 km s{sup -1} and {approx}150 km s{sup -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.

• OSTI ID: 21394257
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 711; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BINARY STARS
DWARF STARS
ELECTROMAGNETIC RADIATION
EMISSION
ERUPTIVE VARIABLE STARS
IONIZATION
IONIZING RADIATIONS
NOVAE
PHOTOIONIZATION
PHOTON EMISSION
RADIATION SOURCES
RADIATIONS
SPECTRA
STARS
VARIABLE STARS
WHITE DWARF STARS
X RADIATION
X-RAY SPECTRA