LOSS's First Supernova? New Limits on the "Impostor" SN 1997bs

TL;DR

This study uses late-time space telescope observations to investigate whether SN 1997bs was a supernova or an impostor, finding it remains faint and challenging the dust-obscuration models, with the most likely explanation being a subluminous supernova.

Contribution

It provides new late-time observational data of SN 1997bs, challenging existing dust-obscuration models and suggesting it was likely a subluminous Type IIn supernova.

Findings

SN 1997bs remains much fainter than its progenitor.

Dust obscuration models are disfavored.

A subluminous Type IIn SN is the most plausible explanation.

Abstract

We present new, late-time Hubble Space Telescope and Spitzer Space Telescope observations of the archetypal supernova (SN) impostor SN 1997bs. We show that SN 1997bs remains much fainter than its progenitor, posing a challenge for the canonical picture of late-time obscuration by dust forming in a shell ejected during the transient. The possibility that the star survived cloaked behind a dusty, steady wind is also disfavored. The simplest explanation is that SN 1997bs was a subluminous Type IIn SN, although it is currently impossible to rule out the possibility that the star survived either behind an obscuring dusty shell $\gtrsim 1 M_{\odot}$ or with a significantly decreased intrinsic luminosity. Continued monitoring of the system is the most promising means of ultimately resolving the question.