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http://hdl.handle.net/20.500.12386/27541
Title: | SN 2015as: a low-luminosity Type IIb supernova without an early light-curve peak | Authors: | Gangopadhyay, Anjasha Misra, Kuntal PASTORELLO, Andrea Sahu, D. K. TOMASELLA, Lina Tartaglia, L. Singh, Mridweeka Dastidar, Raya Srivastav, S. Ochner, P. Brown, Peter J. Anupama, G. C. BENETTI, Stefano CAPPELLARO, Enrico Kumar, Brajesh Kumar, Brijesh Pandey, S. B. |
Issue Date: | 2018 | Journal: | MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY | Number: | 476 | Issue: | 3 | First Page: | 3611 | Abstract: | We present results of the photometric (from 3 to 509 d post-explosion) and spectroscopic (up to 230 d post-explosion) monitoring campaign of the He-rich Type IIb supernova (SN) 2015as. The (B − V) colour evolution of SN 2015as closely resemble those of SN 2008ax, suggesting that SN 2015as belongs to the SN IIb subgroup that does not show the early, short-duration photometric peak. The light curve of SN 2015as reaches the B-band maximum about 22 d after the explosion, at an absolute magnitude of −16.82 ± 0.18 mag. At ∼75 d after the explosion, its spectrum transitions from that of a SN II to a SN Ib. P Cygni features due to He i lines appear at around 30 d after explosion, indicating that the progenitor of SN 2015as was partially stripped. For SN 2015as, we estimate a <SUP>56</SUP>Ni mass of ∼0.08 M<SUB>☉</SUB> and ejecta mass of 1.1-2.2 M<SUB>☉</SUB>, which are similar to the values inferred for SN 2008ax. The quasi-bolometric analytical light-curve modelling suggests that the progenitor of SN 2015as has a modest mass (∼0.1 M<SUB>☉</SUB>), a nearly compact (∼0.05 × 10<SUP>13</SUP> cm) H envelope on top of a dense, compact (∼2 × 10<SUP>11</SUP> cm) and a more massive (∼1.2 M<SUB>☉</SUB>) He core. The analysis of the nebular phase spectra indicates that ∼0.44 M<SUB>☉</SUB> of O is ejected in the explosion. The intensity ratio of the [Ca ii]/[O i] nebular lines favours either a main-sequence progenitor mass of ∼15 M<SUB>☉</SUB> or a Wolf-Rayet star of 20 M<SUB>☉</SUB>. | URI: | http://hdl.handle.net/20.500.12386/27541 | URL: | https://academic.oup.com/mnras/article-abstract/476/3/3611/4898084?redirectedFrom=fulltext | ISSN: | 0035-8711 | DOI: | 10.1093/mnras/sty478 | Bibcode ADS: | 2018MNRAS.476.3611G | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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