A late-time view of the progenitor candidates of the Type II-P SN 2009ib and SN 2012ec

TL;DR

This study uses late-time Hubble observations to verify progenitor candidates of two Type II-P supernovae, finding one candidate was a blend of stars and the other confirmed to have disappeared, refining our understanding of supernova progenitors.

Contribution

The paper provides the first late-time confirmation of progenitor disappearance for SN 2012ec and clarifies the nature of the progenitor candidate for SN 2009ib, addressing the red supergiant problem.

Findings

SN 2009ib progenitor candidate is a blend of unresolved stars.

No significant brightness change for SN 2009ib's candidate after explosion.

SN 2012ec progenitor candidate faded, confirming its disappearance.

Abstract

The progenitors of Type II-P supernovae (SNe) are generally considered to be red supergiants; however, the so-called "red supergiant problem" indicates that a deeper investigation into the progenitors of this class of SNe is necessary. SN 2009ib and SN 2012ec are two Type II-P SNe for which progenitor candidates have been identified in pre-explosion images. In this work, we use new, late-time Hubble Space Telescope observations to search for the disappearance of these two candidates and confirm their nature. In the case of SN 2009ib, the late-time high-resolution imaging reveals that the progenitor candidate is in fact a blend of multiple unresolved stars. Subsequent difference imaging shows no significant change in brightness at the SN's position even years after the explosion. These findings indicate that the flux from the previously identified source is dominated by unresolved field stars, with little to no contribution from the genuine progenitor. In the case of SN 2012ec, a comparison of pre-explosion and late-time images reveals that the progenitor candidate faded by about 0.6 mag in the F814W band seven years after the explosion, confirming the disappearance of the progenitor.