The Candidate Progenitor of the Type IIn SN 2010jl is Not an Optically
  Luminous Star
  The nature of the progenitor star (or system) for the Type IIn supernova (SN)
subclass remains uncertain. While there are direct imaging constraints on the
progenitors of at least four Type IIn supernovae, one of them being SN 2010jl,
ambiguities remain in the interpretation of the unstable progenitors and the
explosive events themselves. A blue source in pre-explosion HST/WFPC2 images
falls within the 5 sigma astrometric error circle derived from post-explosion
ground-based imaging of SN 2010jl. At the time the ground-based astrometry was
published, however, the SN had not faded sufficiently for post-explosion HST
follow-up observations to determine a more precise astrometric solution and/or
confirm if the pre-explosion source had disappeared, both of which are
necessary to ultimately disentangle the possible progenitor scenarios. Here we
present HST/WFC3 imaging of the SN 2010jl field obtained in 2014 and 2015, when
the SN had faded sufficiently to allow for new constraints on the progenitor.
The SN, which is still detected in the new images, is offset by 0."099 +/-
0."008 (24 +/- 2 pc) from the underlying and extended source of emission that
contributes at least partially, if not entirely, to the blue source previously
suggested as the candidate progenitor in the WFPC2 data. This point alone rules
out the possibility that the blue source in the pre-explosion images is the
exploding star, but may instead suggest an association with a young (<5-6 Myr)
cluster and still argues for a massive (>30 solar masses) progenitor. We obtain
new upper limits on the flux from a single star at the SN position in the
pre-explosion WFPC2 and Spitzer/IRAC images that may ultimately be used to
constrain the progenitor properties.
