2005/10/03 by J. -U. Ness, J.- U. Ness, S. Starrfield +3 · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Black-body radiation #Doubly ionized oxygen #Emission spectrum #Grating #Line (geometry) #Luminosity #RADIUS #Spectral line #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2005.09664.x
published as Mon.Not.Roy.Astron.Soc.364:1015-1024,2005 · 11 pages, 8 figures, accepted for MNRAS
arxiv created 2005/10/03 · openalex publication_date 2005/11/07 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
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 × 1027 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 Lyα/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 × 1036 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.