Paper

The Dusty Progenitor Star of the Type II Supernova 2017eaw

Kilpatrick, Charles D, Foley, Ryan J

2018

Overview

We present pre-explosion photometry of the likely progenitor star of the Type II supernova (SN II) 2017eaw in NGC 6946. We use a Hubble Space Telescope (HST) image of SN 2017eaw to perform relative astrometry with HST and Spitzer Space Telescope (Spitzer) imaging, finding a single point source consistent with its position. We detect the progenitor star in \\(>\\)40 epochs of HST and Spitzer imaging covering 12.9 years to 43 days before discovery. While the progenitor luminosity was roughly constant for most of this period, there was a \\(\\sim\\)20% increase in its \\(4.5~\\mu\\)m luminosity over the final 3 years before explosion. We interpret the bright mid-infrared emission as a signature of circumstellar dust around the progenitor system. Using the pre-explosion photometry and assuming some circumstellar dust, we find the progenitor is most likely a red supergiant with \\(\\log(L/L_{\\odot}) = 4.9\\) and \\(T = 3350\\) K, obscured by a \\(>2\\times10^{-5}~M_{\\odot}\\) dust shell with \\(R = 4000~R_{\\odot}\\) and \\(T = 960\\) K. Comparing to single-star evolutionary tracks, we find that the progenitor star had an initial mass of \\(13~M_{\\odot}\\) and a mass-loss rate of \\(2\\times10^{-7}~M_{\\odot}~\\text{yr}^{-1}\\), consistent with the population of SN II progenitor stars.

• Publisher: Cornell University Library, arXiv.org
• Subject: Astrometry / Cosmic dust / Explosions / Hubble Space Telescope / Infrared signatures / Luminosity / Photometry / Space telescopes / Stellar evolution