2009/02/14 by Izumi Hachisu, Mariko Kato · 1 citation
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Gamma-ray bursts and supernovae #astro-ph.HE #astro-ph.SR
paper · pdf · doi:10.1088/0004-637x/694/2/l103
4 pages including 4 figures, to appear in the Astrophysical Journal, Letters
arxiv created 2009/02/14 · openalex publication_date 2009/03/09 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
V2491 Cygni (Nova Cygni 2008 No. 2) was detected as a transient supersoft X-ray source with the Swift XRT as early as 40 days after the outburst, suggesting a very massive white dwarf (WD) close to the Chandrasekhar limit. We present a unified model of near infrared, optical, and X-ray light curves for V2491 Cyg, and have estimated, from our best-fit model, the WD mass to be 1.3 ± 0.02 M ☉ with an assumed chemical composition of the envelope, X = 0.20, Y = 0.48, X CNO = 0.20, X Ne = 0.10, and Z = 0.02 by mass weight. We strongly recommend detailed composition analysis of the ejecta because some enrichment of the WD matter suggests that the WD mass does not increase like in RS Oph, which is a candidate of Type Ia supernova progenitors. V2491 Cyg shows a peculiar secondary maximum in the optical light curve as well as V1493 Aql and V2362 Cyg. Introducing magnetic activity as an adding energy source to nuclear burning, we propose a physical mechanism of the secondary maxima.