THE SUPERSOFT X-RAY PHASE OF NOVA RS OPHIUCHI 2006

Journal Article · Mon Jan 31 23:00:00 EST 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/727/2/124· OSTI ID:21567520

Osborne, J P; Page, K L; Beardmore, A P; Goad, M R ^[1]; Bode, M F ^[2]; O'Brien, T J ^[3]; Starrfield, S ^[4]; Rauch, T ^[5]; Ness, J -U ^[6]; Krautter, J ^[7]; Schwarz, G ^[8]; Burrows, D N ^[9]; Gehrels, N ^[10]; Drake, J J ^[11]; Evans, A ^[12]; Eyres, S P. S., ^[13]

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1. Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH (United Kingdom)
2. Astrophysics Research Institute, Liverpool John Moores University, Birkenhead, CH41 1LD (United Kingdom)
3. Jodrell Bank Observatory, School of Physics and Astronomy, University of Manchester, Macclesfield, SK11 9DL (United Kingdom)
4. School of Earth and Space Exploration, Arizona State University, P. O. Box 871404, Tempe, AZ 85287-1404 (United States)
5. Institute for Astronomy and Astrophysics, Kepler Center for Astro and Particle Physics, Eberhard Karls University, Sand 1, D-72076 Tuebingen (Germany)
6. XMM-Newton Science Operations Centre, ESAC, Apartado 78, 28691 Villanueva de la Canada, Madrid (Spain)
7. Landessternwarte, Koenigstuhl, 69117 Heidelberg (Germany)
8. American Astronomical Society, 2000 Florida Ave., NW, Suite 400, DC 20009-1231 (United States)
9. Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)
10. NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
11. Smithsonian Astrophysical Observatory, 60 Garden St., MS 3, Cambridge, MA 02138 (United States)
12. Astrophysics Group, School of Physical and Geographical Sciences, Keele University, Staffordshire, ST5 5BG (United Kingdom)
13. Jeremiah Horrocks Institute, University of Central Lancashire, Preston, PR1 2HE (United Kingdom)

Swift X-ray observations of the {approx}60 day supersoft phase of the recurrent nova RS Ophiuchi (RS Oph) 2006 show the progress of nuclear burning on the white dwarf (WD) in exquisite detail. First seen 26 days after the optical outburst, this phase started with extreme variability likely due to variable absorption, although intrinsic WD variations are not excluded. About 32 days later, a steady decline in count rate set in. NLTE model atmosphere spectral fits during the supersoft phase show that the effective temperature of the WD increases from {approx}65 eV to {approx}90 eV during the extreme variability phase, falling slowly after about day 60 and more rapidly after day 80. The bolometric luminosity is seen to be approximately constant and close to Eddington from day 45 up to day 60, the subsequent decline possibly signaling the end of extensive nuclear burning. Before the decline, a multiply-periodic {approx}35 s modulation of the soft X-rays was present and may be the signature of a nuclear fusion driven instability. Our measurements are consistent with a WD mass near the Chandrasekhar limit; combined with a deduced accumulation of mass transferred from its binary companion, this leads us to suggest that RS Oph is a strong candidate for a future supernova explosion. The main uncertainty now is whether the WD is the CO type necessary for a Type Ia supernova. This may be confirmed by detailed abundance analyses of spectroscopic data from the outbursts.

• OSTI ID: 21567520
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 727; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BINARY STARS
DWARF STARS
ELECTROMAGNETIC RADIATION
ERUPTIVE VARIABLE STARS
IONIZING RADIATIONS
NOVAE
OSCILLATIONS
RADIATIONS
SOFT X RADIATION
STARS
VARIABLE STARS
WHITE DWARF STARS
X RADIATION