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 NH = 1.2 × 1021 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/Lyβ 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 × 105 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 language | English (US) |
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Pages (from-to) | 1015-1024 |
Number of pages | 10 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 364 |
Issue number | 3 |
DOIs | |
State | Published - 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