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GW Librae : a unique laboratory for pulsations in an accreting white dwarf
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(2016) GW Librae : a unique laboratory for pulsations in an accreting white dwarf. Monthly Notices of the Royal Astronomical Society, 459 (4). pp. 3929-3938. doi:10.1093/mnras/stw838 ISSN 0035-8711.
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Official URL: http://dx.doi.org/10.1093/mnras/stw838
Abstract
Non-radial pulsations have been identified in a number of accreting white dwarfs in cataclysmic variables. These stars offer insight into the excitation of pulsation modes in atmospheres with mixed compositions of hydrogen, helium, and metals, and the response of these modes to changes in the white dwarf temperature. Among all pulsating cataclysmic variable white dwarfs, GW Librae stands out by having a well-established observational record of three independent pulsation modes that disappeared when the white dwarf temperature rose dramatically following its 2007 accretion outburst. Our analysis of HST ultraviolet spectroscopy taken in 2002, 2010 and 2011, showed that pulsations produce variations in the white dwarf effective temperature as predicted by theory. Additionally in May 2013, we obtained new HST/COS ultraviolet observations that displayed unexpected behaviour: besides showing variability at '275 s, which is close to the post-outburst pulsations detected with HST in 2010 and 2011, the white dwarf exhibits high-amplitude variability on a '4.4 h time-scale. We demonstrate that this variability is produced by an increase of the temperature of a region on white dwarf covering up to '30 per cent of the visible white dwarf surface. We argue against a short-lived accretion episode as the explanation of such heating, and discuss this event in the context of non-radial pulsations on a rapidly rotating star.
Item Type: | Journal Article | ||||||||
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Subjects: | Q Science > QB Astronomy | ||||||||
Divisions: | Faculty of Science, Engineering and Medicine > Science > Physics | ||||||||
Library of Congress Subject Headings (LCSH): | White dwarf stars, Hubble Space Telescope (Spacecraft) | ||||||||
Journal or Publication Title: | Monthly Notices of the Royal Astronomical Society | ||||||||
Publisher: | Oxford University Press | ||||||||
ISSN: | 0035-8711 | ||||||||
Official Date: | 11 July 2016 | ||||||||
Dates: |
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Volume: | 459 | ||||||||
Number: | 4 | ||||||||
Page Range: | pp. 3929-3938 | ||||||||
DOI: | 10.1093/mnras/stw838 | ||||||||
Status: | Peer Reviewed | ||||||||
Publication Status: | Published | ||||||||
Access rights to Published version: | Restricted or Subscription Access | ||||||||
Date of first compliant deposit: | 12 April 2016 | ||||||||
Date of first compliant Open Access: | 11 August 2016 | ||||||||
Funder: | Seventh Framework Programme (European Commission) (FP7), European Research Council (ERC), Hubble Space Telescope (Spacecraft) (HST), United States. National Aeronautics and Space Administration (NASA) | ||||||||
Grant number: | Grant no. 320964 (ERC), #HST-HF2-51357.001-A, NAS5-26555 (NASA) |
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