Supernova Progenitors, Their Variability, and the Type IIP Supernova ASASSN-16fq in M66

• Main Authors: Kochanek, C. S, Fraser, M, Adams, S. M, Sukhbold, T, Prieto, J. L, Muller, T, Bock, G, Brown, J. S, Dong, Subo, Holoien, T. W. -S, Khan, R, Shappee, B. J, Stanek, K. Z
• Format: Journal Article
• Language: English
• Published: 31-08-2016
• Subjects: Physics - Astrophysics of Galaxies; Physics - High Energy Astrophysical Phenomena; Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.1609.00022

We identify a pre-explosion counterpart to the nearby Type IIP supernova
ASASSN-16fq (SN 2016cok) in archival Hubble Space Telescope (HST) 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<17Msun,
and was most likely in the mass range 8-12Msun. Observations once ASASSN-16fq
has faded will have no difficulty accurately determining the properties of the
progenitor. In 8 years of Large Binocular Telescope (LBT) data, no significant
progenitor variability is detected to RMS limits of roughly 0.03 mag. Of the
six nearby SN with constraints on 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%
confidence limit implied by these sources on the number of outbursts over the
last decade before the SN that last longer than 0.1 years (FWHM) and are
brighter than M_R<-8 mag is approximately N<3. Our continuing LBT monitoring
program will steadily improve constraints on pre-SN progenitor variability at
amplitudes far lower than achievable by SN surveys.