Supernova progenitors, their variability and the Type IIP Supernova ASASSN-16fq in M66

Abstract
We identify a pre-explosion counterpart to the nearby Type IIP supernova ASASSN-16fq (SN 2016cok) in archival Hubble Space Telescope data. The source appears to be a blend of several stars that prevents obtaining accurate photometry. However, with reasonable assumptions about the stellar temperature and extinction, the progenitor almost certainly had an initial mass M-* less than or similar to 17M(circle dot), and was most likely in the mass range of M-* = 8-12M(circle dot). Observations once ASASSN-16fq has faded will have no difficulty accurately determining the properties of the progenitor. In 8 yr of Large Binocular Telescope (LBT) data, no significant progenitor variability is detected to rms limits of roughly 0.03 mag. Of the six nearby supernova (SN) with constraints on the low-level variability, SN 1987A, SN 1993J, SN 2008cn, SN 2011dh, SN 2013ej and ASASSN-16fq, only the slowly fading progenitor of SN 2011dh showed clear evidence of variability. Excluding SN 1987A, the 90 per cent confidence limit implied by these sources on the number of outbursts over the last decade before the SN that last longer than 0.1 yr (full width at half-maximum) and are brighter than M-R < -8 mag is approximately N-out less than or similar to 3. Our continuing LBT monitoring programme will steadily improve constraints on pre-SN progenitor variability at amplitudes far lower than achievable by SN surveys.
Description
Keywords
stars: massive, supernovae: general, supernovae: individual: SN 2016cok, galaxies: individual: M 66, CORE-COLLAPSE SUPERNOVAE, DIGITAL SKY SURVEY, RED SUPERGIANT PROGENITOR, MASSIVE STARS, SN 2012AW, CIRCUMSTELLAR DUST, FAILED SUPERNOVAE, NEARBY GALAXIES, ETA-CARINAE, EXPLOSION
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