Observational Signature of Circumstellar Interaction and 56Ni-mixing in the Type II Supernova 2016gfy

Avinash Singh, Brajesh Kumar, Takashi J. Moriya, G. C. Anupama, D. K. Sahu, Peter J. Brown, Jennifer E. Andrews, Nathan Smith

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11 Scopus citations


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 o, a progenitor radius of ∼350-700 R o, a progenitor mass of ∼12-15 M o, 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 o 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 o yr-1 is estimated for NGC 2276 using the archival GALEX FUV data.

Original languageEnglish (US)
Article number68
JournalAstrophysical Journal
Issue number1
StatePublished - Sep 1 2019


  • galaxies: individual (NGC 2276)
  • supernovae: general
  • supernovae: individual (SN 2016gfy)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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