The impostor revealed: SN 2016jbu was a terminal explosion

Abstract

In this Letter, we present recent observations from the Hubble Space Telescope of the interacting transient SN 2016jbu at +5 yr. We find no evidence for any additional outburst from SN 2016jbu, and the optical source has now faded significantly below the progenitor magnitudes from early 2016. Similar to recent observations of SN 2009ip and SN 2015bh, SN 2016jbu has not undergone a significant change in colour over the past 2 years, suggesting that there is a lack of ongoing dust formation. We find that SN 2016jbu is fading more slowly than expected of radioactive nickel, but faster than the decay of SN 2009ip. The late-time light curve displays a nonlinear decline and follows on from a re-brightening event that occurred ∼8 months after peak brightness, suggesting CSM interaction continues to dominate SN 2016jbu. While our optical observations are plausibly consistent with a surviving, hot, dust-enshrouded star, this would require an implausibly large dust mass. These new observations suggest that SN 2016jbu is a genuine, albeit strange, supernova, and we discuss the plausibility of a surviving binary companion.