VLT detection of a red supergiant progenitor of the type IIP supernova 2008bk

TL;DR

This study identifies a red supergiant star as the progenitor of supernova 2008bk using high-resolution pre-explosion images, providing direct evidence of the star's nature and mass before explosion.

Contribution

First direct detection and characterization of a red supergiant progenitor for a type IIP supernova using VLT pre-explosion imaging.

Findings

Progenitor is a red supergiant with initial mass ~8.5 Msun.

Precise localization of the progenitor in pre-explosion images.

Consistent with stellar evolutionary models.

Abstract

We report the identification of a source coincident with the position of the nearby type II-P supernova (SN) 2008bk in high quality optical and near-infrared pre-explosion images from the ESO Very Large Telescope (VLT). The SN position in the optical and near-infrared pre-explosion images is identified to within about +-70 and +-40 mas, respectively, using post-explosion Ks-band images obtained with the NAOS CONICA adaptive optics system on the VLT. The pre-explosion source detected in four different bands is precisely coincident with SN 2008bk and is consistent with being dominated by a single point source. We determine the nature of the point source using the STARS stellar evolutionary models and find that its colours and luminosity are consistent with the source being a red supergiant progenitor of SN 2008bk with an initial mass of 8.5 +- 1.0 Msun.