Updated Photometry of the Yellow Supergiant Progenitor and Late-time Observations of the Type IIb Supernova SN 2016gkg

Charles D. Kilpatrick*, David A. Coulter, Ryan J. Foley, Anthony L. Piro, Armin Rest, César Rojas-Bravo, Matthew R. Siebert

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

We present Hubble Space Telescope (HST) observations of the Type IIb supernova (SN) SN 2016gkg at 652, 1698, and 1795 days from explosion with the Advanced Camera for Surveys (ACS) and Wide Field Camera 3 (WFC3). Comparing to pre-explosion imaging from 2001 obtained with the Wide Field Planetary Camera 2, we demonstrate that SN 2016gkg is now fainter than its candidate counterpart in the latest WFC3 imaging, implying that the counterpart has disappeared and confirming that it was the SN progenitor star. We show the latest light curve and Keck spectroscopy of SN 2016gkg, which imply that SN 2016gkg is declining more slowly than the expected rate for 56Co decay during its nebular phase. We find that this emission is too luminous to be powered by other radioisotopes and infer that SN 2016gkg is entering a new phase in its evolution where it is powered primarily by interaction with circumstellar matter. Finally, we reanalyze the progenitor star spectral energy distribution and late-time limits in the context of binary evolution models. Including emission from a potential companion star, we find that all such predicted companion stars would be fainter than our limiting magnitudes.

Original languageEnglish (US)
Article number111
JournalAstrophysical Journal
Volume936
Issue number2
DOIs
StatePublished - Sep 1 2022

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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