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 language | English (US) |
|---|---|
| Article number | 111 |
| Journal | Astrophysical Journal |
| Volume | 936 |
| Issue number | 2 |
| DOIs | |
| State | Published - Sep 1 2022 |
Funding
We would like to thank I. Arcavi and A. Gilkis for helpful comments related to this manuscript. This work includes data obtained with the Swope Telescope at Las Campanas Observatory, Chile, as part of the Swope Time Domain Key Project (PI: Piro; Co-Is: Burns, Cowperthwaite, Dimitriadis, Drout, Foley, French, Holoien, Hsiao, Kilpatrick, Madore, Phillips, and Rojas-Bravo). The Hubble Space Telescope imaging presented in this manuscript comes from programs GO-9042 (PI: Smartt), GO-15272 (PI: Folatelli), GO-16287 (PI: Lyman), and SNAP-16179 (PI: Filippenko). Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. We would like to thank I. Arcavi and A. Gilkis for helpful comments related to this manuscript. This work includes data obtained with the Swope Telescope at Las Campanas Observatory, Chile, as part of the Swope Time Domain Key Project (PI: Piro; Co-Is: Burns, Cowperthwaite, Dimitriadis, Drout, Foley, French, Holoien, Hsiao, Kilpatrick, Madore, Phillips, and Rojas-Bravo). The Hubble Space Telescope imaging presented in this manuscript comes from programs GO-9042 (PI: Smartt), GO-15272 (PI: Folatelli), GO-16287 (PI: Lyman), and SNAP-16179 (PI: Filippenko). Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science