Properties of the Candidate Progenitor of SN 2011dh in M51
ATel #3401; W. Li, A. V. Filippenko (University of California, Berkeley), and S. D. Van Dyk (Spitzer Science Center, California Institute of Technology)
on 3 Jun 2011; 19:05 UT
Credential Certification: Alexei V. Filippenko (alex@astro.berkeley.edu)
Subjects: Infra-Red, Optical, Supernovae, Transient
We report further preliminary analysis of Hubble Space Telescope
images of the SN 2011dh candidate progenitor
(ATEL #3398, #3399; CBET #2736). The object has F435W (B) = 22.4 +/- 0.01 mag, F555W (V) =
21.84 +/- 0.01 mag, and F814W (I) = 21.22 +/- 0.01 mag. Assuming
negligible host-galaxy reddening for the SN, and a distance modulus to
M51 of 29.6 mag (Richmond et al. 1996, AJ, 111, 327), the object has
M(I) = -8.4 mag, with color V - I = 0.6 mag, and B - V = 0.6 mag. If
this bright source in the center of the SN location error radius is
indeed the progenitor of SN 2011dh, its properties are similar to
those reported for the progenitor of the Type II-L (or
spectroscopically peculiar II-P) SN 2009kr (Elias-Rosa et al. 2010,
ApJ, 714, L254; Fraser et al. 2010, ApJ, 714, L280), and it is
consistent with a highly luminous yellow supergiant with an initial
mass of 18-24 solar masses. Other possibilities are that (a) the
bright source is a compact star cluster, with the progenitor of SN
2011dh being a member of the cluster, or (b) the bright source is
unrelated to SN 2011dh, and the progenitor of SN 2011dh is obscured by
this object. We encourage efforts to secure high-resolution images of
the field to improve the astrometric precision.
