An X-ray emission-line spectrum of Nova V382 Velorum 1999

J. U. Ness, Sumner Starrfield, C. Jordan, J. Krautter, J. H M M Schmitt

Research output: Contribution to journalArticle

29 Scopus citations

Abstract

We report on the analysis of an X-ray grating spectrum of the Classical Nova V382 Vel (1999), obtained with the Low Energy Transmission Grating (LETG)+HRC-S instrument onboard Chandra, which shows emission lines dominating over any continuum. Lines of Si, Mg, Ne, O, N and C are identified, but no Fe lines are detected. The total luminosity in the lines is ∼4 × 10 27 erg s -1 (corrected for N H = 1.2 × 10 21 cm -2). The lines have broad profiles with full width at half-maximum corresponding to a velocity ∼2900 × 200 km s -1. Some structure is identified in the profiles, but for different elements we find different profile structures. While lines of O show a broadened Gaussian profile, those of Ne are double-peaked, suggesting a fragmented emitting plasma. Using the emission measure distribution, we derive relative element abundances and find abundances of Ne and N that are significantly enhanced relative to that of O, while Fe is not overabundant. The lack of any source emission longwards of 50 Å and the O VIII Ly α/Ly β line ratio supports previous values of the hydrogen column density. We find weak continuum emission from the white dwarf, consistent with a blackbody spectrum with an upper limit to the temperature of T = 3 × 10 5 K, assuming a source radius of 6000 km. The upper limit for the integrated blackbody luminosity is 2 × 10 36 erg s -1. The BeppoSAX and Chandra ACIS observations of V382 Vel show that the nova was bright and in the Super-Soft phase as late as 1999 December 30. Our LETG observation obtained 6 weeks later, as well as all subsequent X-ray observations, showed a remarkable fading to a nearly pure emission line phase which suggests that nuclear burning on the white dwarf had turned off by February. In the absence of a photoionizing source, the emission lines were formed in a collisionally ionized and excited expanding shell.

Original languageEnglish (US)
Pages (from-to)1015-1024
Number of pages10
JournalMonthly Notices of the Royal Astronomical Society
Volume364
Issue number3
DOIs
StatePublished - Dec 11 2005

Keywords

  • Stars: individual: V382 Vel
  • Stars: novae, cataclysmic variables
  • Stars: white dwarfs
  • X-rays: binaries
  • X-rays: individual: V382 Vel

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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