http://arxiv.org/abs/1808.02989
We report the first detection of a credible progenitor system for a Type Ic supernova (SN Ic), SN 2017ein. We present spectra and photometry of the SN, finding it to be similar to carbon-rich, low-luminosity SNe Ic. Using a post-explosion Keck adaptive optics image, we precisely determine the position of SN 2017ein in pre-explosion \hst\ images, finding a single source coincident with the SN position. This source is marginally extended, and is consistent with being a stellar cluster. However, under the assumption that the emission of this source is dominated by a single point source, we perform point-spread function photometry, and correcting for line-of-sight reddening, we find it to have $M_{\rm F555W} = -7.5\pm0.2$ mag and $m_{\rm F555W}-m_{\rm F814W}$=$-0.67\pm0.14$ mag. This source is bluer than the main sequence and brighter than almost all Wolf-Rayet stars, however it is similar to some WC+O- and B-star binary systems. Under the assumption that the source is dominated by a single star, we find that it had an initial mass of $55\substack{+20-15} M_{\odot}$. We also examined binary star models to look for systems that match the overall photometry of the pre-explosion source and found that the best-fitting model is a $80$+$48 M_{\odot}$ close binary system in which the $80 M_{\odot}$ star is stripped and explodes as a lower mass star. Late-time photometry after the SN has faded will be necessary to cleanly separate the progenitor star emission from the additional coincident emission.
C. Kilpatrick, T. Takaro, R. Foley, et. al.
Fri, 10 Aug 18
17/45
Comments: 13 pages, 8 figures, published in MNRAS