Journal Article

Kepler observations of V447 Lyr: an eclipsing U Gem Cataclysmic Variable

Gavin Ramsay, John K. Cannizzo, Steve B. Howell, Matt A. Wood, Martin Still, Thomas Barclay and Alan Smale

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 425, issue 2, pages 1479-1485
Published in print September 2012 | ISSN: 0035-8711
Published online September 2012 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2012.21657.x
Kepler observations of V447 Lyr: an eclipsing U Gem Cataclysmic Variable

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Abstract

We present the results of an analysis of Kepler data covering 1.5 yr of the dwarf nova V447 Lyr. We detect eclipses of the accretion disc by the mass donating secondary star every 3.74 h which is the binary orbital period. V447 Lyr is therefore the first dwarf nova in the Kepler field to show eclipses. We also detect five long outbursts and six short outbursts showing V447 Lyr is a U Gem-type dwarf nova. We show that the orbital phase of the mid-eclipse occurs earlier during outbursts compared to quiescence and that the width of the eclipse is greater during outburst. This suggests that the bright spot is more prominent during quiescence and that the disc is larger during outburst than quiescence. This is consistent with an expansion of the outer disc radius due to the presence of high viscosity material associated with the outburst, followed by a contraction in quiescence due to the accretion of low angular momentum material. We note that the long outbursts appear to be triggered by a short outburst, which is also observed in the super-outbursts of SU UMa dwarf novae as observed using Kepler.

Keywords: accretion, accretion discs; stars: dwarf novae; stars: individual: V447 Lyr; novae, cataclysmic variables

Journal Article.  3943 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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