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The X-ray and extreme-ultraviolet flux evolution of SS Cygni throughout outburst
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Wheatley, P. J., Mauche, Christopher W. and Mattei, Janet A. (2003) The X-ray and extreme-ultraviolet flux evolution of SS Cygni throughout outburst. Monthly Notices of the Royal Astronomical Society, 345 (1). pp. 49-61. doi:10.1046/j.1365-8711.2003.06936.x ISSN 0035-8711.
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Official URL: http://dx.doi.org/10.1046/j.1365-8711.2003.06936.x
Abstract
We present the most complete multiwavelength coverage of any dwarf nova outburst: simultaneous optical, Extreme Ultraviolet Explorer and Rossi X-ray Timing Explorer observations of SS Cygni throughout a narrow asymmetric outburst. Our data show that the high-energy outburst begins in the X-ray waveband 0.9–1.4 d after the beginning of the optical rise and 0.6 d before the extreme-ultraviolet rise. The X-ray flux drops suddenly, immediately before the extreme-ultraviolet flux rise, supporting the view that both components arise in the boundary layer between the accretion disc and white dwarf surface. The early rise of the X-ray flux shows that the propagation time of the outburst heating wave may have been previously overestimated.
The transitions between X-ray and extreme-ultraviolet dominated emission are accompanied by intense variability in the X-ray flux, with time-scales of minutes. As detailed by Mauche & Robinson, dwarf nova oscillations are detected throughout the extreme-ultraviolet outburst, but we find they are absent from the X-ray light curve.
X-ray and extreme-ultraviolet luminosities imply accretion rates of 3 × 1015 g s−1 in quiescence, 1 × 1016 g s−1 when the boundary layer becomes optically thick, and ∼1018 g s−1 at the peak of the outburst. The quiescent accretion rate is two and a half orders of magnitude higher than predicted by the standard disc instability model, and we suggest this may be because the inner accretion disc in SS Cyg is in a permanent outburst state.
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): | Accretion (Astrophysics), Cataclysmic variable stars, Dwarf novae | ||||||
Journal or Publication Title: | Monthly Notices of the Royal Astronomical Society | ||||||
Publisher: | Oxford University Press | ||||||
ISSN: | 0035-8711 | ||||||
Official Date: | 2003 | ||||||
Dates: |
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Volume: | 345 | ||||||
Number: | 1 | ||||||
Page Range: | pp. 49-61 | ||||||
DOI: | 10.1046/j.1365-8711.2003.06936.x | ||||||
Status: | Peer Reviewed | ||||||
Publication Status: | Published | ||||||
Date of first compliant deposit: | 6 January 2017 | ||||||
Date of first compliant Open Access: | 11 January 2017 | ||||||
Funder: | University of Leicester, Lawrence Berkeley laboratory, United States. National Aeronautics and Space Administration (NASA) | ||||||
Grant number: | Contract No. W-7405-Eng-48 (Lawrence Berkeley laboratory), Grant NAG5-7027 (NASA) | ||||||
Open Access Version: |
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