LOSS's first supernova? New limits on the `impostor' SN 1997bs

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 disfavoured. 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 ≳1 M_⊙ or with a significantly decreased intrinsic luminosity. Continued monitoring of the system is the most promising means of ultimately resolving the question.