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SN 2015as: a low-luminosity Type IIb supernova without an early light-curve peak

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dc.contributor.author Gangopadhyay, A
dc.contributor.author Misra, K
dc.contributor.author Pastorello, A
dc.contributor.author Sahu, D. K
dc.contributor.author Tomasella, L
dc.contributor.author Tartaglia, L
dc.contributor.author Singh, M
dc.contributor.author Dastidar, R
dc.contributor.author Srivastav, S
dc.contributor.author Ochner, P
dc.contributor.author Brown, P. J
dc.contributor.author Anupama, G. C
dc.contributor.author Benetti, S
dc.contributor.author Cappellaro, E
dc.contributor.author Brajesh Kumar
dc.contributor.author Kumar, B
dc.contributor.author Pandey, S. B
dc.date.accessioned 2020-11-11T01:42:58Z
dc.date.available 2020-11-11T01:42:58Z
dc.date.issued 2018-05
dc.identifier.citation Monthly Notices of the Royal Astronomical Society, Vol. 476, No. 3, pp. 3611-3630 en_US
dc.identifier.issn 1365-2966
dc.identifier.uri http://prints.iiap.res.in/handle/2248/6897
dc.description Restricted Access © Royal Astronomical Society; https://doi.org/10.1093/mnras/sty478 en_US
dc.description.abstract We present results of the photometric (from 3 to 509 days past explosion) and spectroscopic (up to 230 days past 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 days after the explosion, at an absolute magnitude of -16.82 ± 0.18 mag. At ∼ 75 days 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 days after explosion, indicating that the progenitor of SN 2015as was partially stripped. For SN 2015as, we estimate a 56Ni mass of ∼ 0.08 M⊙ and ejecta mass of 1.1–2.2 M⊙, 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⊙), a nearly-compact (∼ 0.05× 1013 cm) H envelope on top of a dense, compact (∼ 2× 1011 cm) and a more massive (∼ 1.2 M⊙) He core. The analysis of the nebular phase spectra indicates that ∼ 0.44 M⊙ 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⊙ or a Wolf Rayet star of 20 M⊙. en_US
dc.language.iso en en_US
dc.publisher Oxford University Press on behalf of the Royal Astronomical Society en_US
dc.subject Supernovae: general en_US
dc.subject Techniques: spectroscopic en_US
dc.subject Supernovae: individual: SN 2015as en_US
dc.subject Galaxies: individual: UGC 5460 en_US
dc.subject Techniques: photometric en_US
dc.title SN 2015as: a low-luminosity Type IIb supernova without an early light-curve peak en_US
dc.type Article en_US

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