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Title: Observational signature of circumstellar Interaction and 56Ni-mixing in the type II supernova 2016gfy
Authors: Singh, A
Brajesh Kumar
Moriya, Takashi J
Anupama, G. C
Sahu, D. K
Brown, Peter J
Andrews, Jennifer E.
Smith, Nathan
Keywords: Galaxies: individual (NGC 2276);Supernovae: general;Supernovae: individual (SN 2016gfy)
Issue Date: 1-Sep-2019
Publisher: IOP Publishing
Citation: The Astrophysical Journal, Vol. 882, No. 1, 68
Abstract: The optical and ultraviolet broadband photometric and spectroscopic observations of the Type II supernova (SN) 2016gfy are presented. The V-band light curve (LC) shows a distinct plateau phase with a slope of s 2 ~ 0.12 mag (100 day)−1 and a duration of 90 ± 5 days. Detailed analysis of SN 2016gfy provided a mean 56Ni mass of 0.033 ± 0.003 M ⊙, a progenitor radius of ~350–700 R ⊙, a progenitor mass of ~12–15 M ⊙, and an explosion energy of (0.9–1.4) × 1051 erg s−1. The P-Cygni profile of Hα in the early-phase spectra (~11–21 days) shows a boxy emission. Assuming that this profile arises from the interaction of the SN ejecta with the pre-existing circumstellar material (CSM), it is inferred that the progenitor underwent a recent episode (30–80 yr prior to the explosion) of enhanced mass loss. Numerical modeling suggests that the early LC peak is reproduced better with an existing CSM of 0.15 M ⊙ spread out to ~70 au. A late-plateau bump is seen in the VRI LCs during ~50–95 days. This bump is explained as a result of the CSM interaction and/or partial mixing of radioactive 56Ni in the SN ejecta. Using strong-line diagnostics, a subsolar oxygen abundance is estimated for the supernova H ii region (12 + log(O/H) = 8.50 ± 0.11), indicating an average metallicity for the host of an SN II. A star formation rate of ~8.5 M ⊙ yr−1 is estimated for NGC 2276 using the archival GALEX FUV data.
Description: Restricted Access
ISSN: 0004-637X
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