X-ray eclipse diagnosis of the evolving mass loss in the recurrent nova U Scorpii 2010

D. Takei, J. J. Drake, M. Tsujimoto, J. U. Ness, J. P. Osborne, Sumner Starrfield, S. Kitamoto

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

We report the Suzaku detection of the earliest X-ray eclipse seen in the recurrent nova U Scorpii 2010. A target-of-opportunity observation 15 days after the outburst found a 27% ± 5% dimming in the 0.2-1.0 keV energy band at the predicted center of an eclipse. In comparison with the X-ray eclipse depths seen at two later epochs by XMM-Newton, the source region shrank by about 10%-20% between days 15 and 35 after the outburst. The X-ray eclipses appear to be deeper than or similar to contemporaneous optical eclipses, suggesting the X-ray and optical source region extents are comparable on day 15. We raise the possibility of the energy dependency in the photon escape regions, and that this would be a result of the supersoft X-ray opacity being higher than the Thomson scattering opacity at the photosphere due to bound-free transitions in abundant metals that are not fully ionized. Assuming a spherically symmetric model, we constrain the mass-loss rate as a function of time. For a ratio of actual to Thomson opacity of 10-100 in supersoft X-rays, we find an ejecta mass of about 10-7-10-6 M .

Original languageEnglish (US)
Article numberL4
JournalAstrophysical Journal Letters
Volume769
Issue number1
DOIs
StatePublished - May 20 2013

Keywords

  • X-rays: stars
  • novae, cataclysmic variables
  • stars: individual (U Scorpii)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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