On the Progenitor of the Type II-Plateau SN 2008cn in NGC 4603

TL;DR

This study identifies a supergiant star as a potential progenitor of SN 2008cn through pre- and post-explosion Hubble images, estimating its initial mass and discussing uncertainties due to distance and stellar blending.

Contribution

It provides the first candidate progenitor for SN 2008cn, estimating its mass and analyzing its properties, while addressing ambiguities in progenitor identification.

Findings

Progenitor candidate has an initial mass of approximately 15 solar masses.

The candidate star appears more yellow than typical for SN II-P progenitors.

If not the progenitor, the undetected star is constrained to be less than 11 solar masses.

Abstract

Through comparison of pre- and post-explosion images obtained with the Wide Field and Planetary Camera 2 onboard the Hubble Space Telescope, we have isolated a supergiant star prior to explosion at nearly the same position as the high-luminosity SN II-P 2008cn. We provide evidence that this supergiant may well be the progenitor of the SN, although this identification is not entirely unambiguous due mainly to the distance to the host galaxy (NGC 4603), 33.3 Mpc. The progenitor candidate has a more yellow color than generally would be expected and, if a single star, would require that it exploded during a "blue loop" evolutionary phase. Nonetheless, we estimate an initial mass of Mini = 15 +/- 2 Msun for this star, which is within the expected mass range for SN II-P progenitors. The yellower color could also arise from the blend of two or more stars, such as a red supergiant hidden by a brighter, blue supergiant; or a massive, interacting binary system. Finally, if the yellow supergiant is not the progenitor, or is not a stellar blend or binary containing the progenitor, then we constrain any undetected progenitor star to be a red supergiant with Mini < 11 Msun, considering a physically more realistic scenario of explosion at the model endpoint luminosity for a rotating star. (ABRIDGED)