The Massive Progenitor of the Type II-Linear SN 2009kr

TL;DR

This paper reports the identification of a highly luminous yellow supergiant as the progenitor of the rare Type II-linear supernova 2009kr, providing new insights into the progenitors of this supernova subclass.

Contribution

It presents the first direct identification of a progenitor star for a Type II-linear supernova, linking progenitor mass to supernova classification.

Findings

SN 2009kr is classified as Type II-linear based on early observations.

A candidate progenitor star was identified as a luminous yellow supergiant.

Progenitor mass estimated at 18-24 solar masses, bridging known supernova progenitor mass ranges.

Abstract

We present early-time photometric and spectroscopic observations of supernova (SN) 2009kr in NGC 1832. We find that its properties to date support its classification as Type II-linear (SN II-L), a relatively rare subclass of core-collapse supernovae (SNe). We have also identified a candidate for the SN progenitor star through comparison of pre-explosion, archival images taken with WFPC2 onboard the Hubble Space Telescope (HST) with SN images obtained using adaptive optics (AO) plus NIRC2 on the 10-m Keck-II telescope. Although the host galaxy's substantial distance (~26 Mpc) results in large uncertainties in the relative astrometry, we find that if this candidate is indeed the progenitor, it is a highly luminous (M_V = -7.8 mag) yellow supergiant with initial mass ~18-24 M_sun. This would be the first time that a SN II-L progenitor has been directly identified. Its mass may be a bridge between the upper initial mass limit for the more common Type II-plateau SNe (SNe II-P) and the inferred initial mass estimate for one Type II-narrow SN (SN IIn).