Ramsay, G. (Gavin), Hakala, P., Marsh, T. R., Nelemans, G., Steeghs, D. (Danny), 1972- and Cropper, Mark. (2005) XMM-Newton observations of AM CVn binaries. Astronomy & Astrophysics, Vol.440 (No.2). pp. 675-681. ISSN 0004-6361

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Abstract

We present the results of XMM-Newton observations of four AM CVn systems – AM CVn, CR Boo, HP Lib and GP Com. Their light curves show very different characteristics. The X-ray light curves show no coherent pulsations, suggesting the accreting white dwarfs have relatively low magnetic field strengths. Their spectra were best modelled using a multi-temperature emission model and a strong UV component. We find that CR Boo and HP Lib have X-ray spectra with abundances consistent with relatively low temperature CNO processed material, while AM CVn and GP Com show an enhancement of nitrogen. A large fraction of the accretion luminosity is emitted in the UV. We determine accretion luminosities of ∼1.6 × 10 33 erg s −1 and 1.7 × 10 31 erg s −1 for AM CVn and GP Com respectively. Comparing the implied mass transfer rates with that derived using model fits to optical and UV spectra, we find evidence that in the case of AM CVn, we do not detect a significant proportion of the accretion energy. This missing component could be lost in the form of a wind.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Cataclysmic variable stars, X-ray sources, Galactic
Journal or Publication Title:	Astronomy & Astrophysics
Publisher:	EDP Sciences
ISSN:	0004-6361
Date:	September 2005
Volume:	Vol.440
Number:	No.2
Page Range:	pp. 675-681
Identification Number:	10.1051/0004-6361:20052950
Status:	Peer Reviewed
Access rights to Published version:	Open Access
Funder:	European Space Agency (ESA), United States. National Aeronautics and Space Administration (NASA), Suomen Akatemia [Academy of Finland], Smithsonian Astrophysical Observatory
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URI:	http://wrap.warwick.ac.uk/id/eprint/3586

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