Pumo, M L
AffiliationUniv Arizona, Dept Astron, 933 N Cherry Ave, Tucson, AZ 85719 USA
Univ Arizona, Steward Observ, 933 N Cherry Ave, Tucson, AZ 85719 USA
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PublisherOXFORD UNIV PRESS
CitationS Benetti, L Zampieri, A Pastorello, E Cappellaro, M L Pumo, N Elias-Rosa, P Ochner, G Terreran, L Tomasella, S Taubenberger, M Turatto, A Morales-Garoffolo, A Harutyunyan, L Tartaglia; ASASSN-15no: the Supernova that plays hide-and-seek, Monthly Notices of the Royal Astronomical Society, Volume 476, Issue 1, 1 May 2018, Pages 261–270, https://doi.org/10.1093/mnras/sty166
Rights© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
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AbstractWe report the results of our follow-up campaign of the peculiar supernova ASASSN-15no, based on optical data covering similar to 300 d of its evolution. Initially the spectra show a pure black-body continuum. After few days, the HeI lambda lambda 5876 transition appears with a P-Cygni profile and an expansion velocity of about 8700 km s(-1). Fifty days after maximum, the spectrum shows signs typically seen in interacting supernovae. A broad (FWHM similar to 8000 km s(-1)) H alpha becomes more prominent with time until similar to 150 d after maximum and quickly declines later on. At these phases Hastarts to show an intermediate component, which together with the blue pseudo-continuum are clues that the ejecta begin to interact with the circumstellar medium (CSM). The spectra at the latest phases look very similar to the nebular spectra of stripped-envelope SNe. The early part (the first 40 d after maximum) of the bolometric curve, which peaks at a luminosity intermediate between normal and superluminous supernovae, is well reproduced by a model in which the energy budget is essentially coming from ejecta recombination and Ni-56 decay. From the model, we infer a mass of the ejecta M-ej = 2.6M(circle dot); an initial radius of the photosphere R-0 = 2.1 x 10(14) cm; and an explosion energy E-expl = 0.8 x 10(51) erg. A possible scenario involves a massive and extended H-poor shell lost by the progenitor star a few years before explosion. The shell is hit, heated, and accelerated by the supernova ejecta. The accelerated shell+ejecta rapidly dilutes, unveiling the unperturbed supernova spectrum below. The outer ejecta start to interact with a H-poor external CSM lost by the progenitor system about 9-90 yr before the explosion.
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SponsorsPRIN-INAF (project 'Transient Universe: unveiling new types of stellar explosions with PESSTO'); German Research Foundation (DFG) [TRR 33]; Alfred P. Sloan Foundation; National Science Foundation; U.S. Department of Energy Office of Science; University of Arizona; Brazilian Participation Group; Brookhaven National Laboratory; Carnegie Mellon University; University of Florida; French Participation Group; German Participation Group; Harvard University; Instituto de Astrofisica de Canarias; Michigan State/Notre Dame/JINA Participation Group; Johns Hopkins University; Lawrence Berkeley National Laboratory; Max Planck Institute for Astrophysics; Max Planck Institute for Extraterrestrial Physics; New Mexico State University; New York University; Ohio State University; Pennsylvania State University; University of Portsmouth; Princeton University; Spanish Participation Group; University of Tokyo; University of Utah; Vanderbilt University; University of Virginia; University of Washington; Yale University