NIR spectra of SN 2014C 1-5yr post-explosion

The delayed interaction suggests a detached CSM shell, unlike in a typical SNIIn where the CSM is much closer and the interaction commences earlier post-explosion, indicating a different mass-loss history. We present infrared observations of SN 2014C 1-5yr post-explosion, including uncommon 9.7{mu}m imaging with COMICS on the Subaru telescope.

Spectroscopy shows the intermediate-width HeI 1.083{mu}m emission from the interacting region up to the latest epoch 1639 days post-explosion. The last Spitzer/IRAC photometry at 1920 days confirms ongoing CSM interaction. The 1-10{mu}m spectral energy distributions (SEDs) can be explained by a dust model with a mixture of 62% carbonaceous and 38% silicate dust, pointing to a chemically inhomogeneous CSM.