Swift observations of the 2006 outburst of the recurrent nova RS ophiuchi. I. Early X-ray emission from the shocked ejecta and red giant wind

M. F. Bode, T. J. O'Brien, J. P. Osborne, K. L. Page, F. Senziani, G. K. Skinner, Sumner Starrfield, J. U. Ness, J. J. Drake, G. Schwarz, A. P. Beardmore, M. J. Darnley, S. P S Eyres, A. Evans, N. Gehrels, M. R. Goad, P. Jean, J. Krautter, G. Novara

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109 Scopus citations

Abstract

RS Ophiuchi began its latest outburst on 2006 February 12. Previous outbursts have indicated that high-velocity ejecta interact with a preexisting red giant wind, setting up shock systems analogous to those seen in supernova remnants. However, in the previous outburst in 1985, X-ray observations did not commence until 55 days after the initial explosion. Here we report on Swift observations covering the first month of the 2006 outburst with the Burst Alert Telescope (BAT) and X-Ray Telescope (XRT) instruments. RS Oph was clearly detected in the BAT 14-25 keV band from t = 0 to t ~ 6 days. XRT observations from 0.3 to 10 keV started 3.17 days after outburst. The rapidly evolving XRT spectra clearly show the presence of both line and continuum emission, which can be fitted by thermal emission from hot gas whose characteristic temperature, overlying absorbing column (NH)W, and resulting unabsorbed total flux decline monotonically after the first few days. Derived shock velocities are in good agreement with those found from observations at other wavelengths. Similarly, (NH)W is in accord with that expected from the red giant wind ahead of the forward shock. We confirm the basic models of the 1985 outburst and conclude that standard phase I remnant evolution terminated by t ~ 6 days and the remnant then rapidly evolved to display behavior characteristic of phase III. Around t = 26 days, however, a new, luminous, and highly variable soft X-ray source began to appear, whose origin will be explored in a subsequent paper.

Original languageEnglish (US)
Pages (from-to)629-635
Number of pages7
JournalAstrophysical Journal
Volume652
Issue number1 I
DOIs
StatePublished - Nov 20 2006

Keywords

  • Binaries: close
  • Binaries: symbiotic
  • Novae, cataclysmic variables
  • Stars: individual (RS Ophiuchi)
  • Supernovae: general
  • White dwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Bode, M. F., O'Brien, T. J., Osborne, J. P., Page, K. L., Senziani, F., Skinner, G. K., Starrfield, S., Ness, J. U., Drake, J. J., Schwarz, G., Beardmore, A. P., Darnley, M. J., Eyres, S. P. S., Evans, A., Gehrels, N., Goad, M. R., Jean, P., Krautter, J., & Novara, G. (2006). Swift observations of the 2006 outburst of the recurrent nova RS ophiuchi. I. Early X-ray emission from the shocked ejecta and red giant wind. Astrophysical Journal, 652(1 I), 629-635. https://doi.org/10.1086/507980