AN OPTICAL STUDY OF THE SUPERLUMINOUS TYPE IIN SUPERNOVA ASASSN-14IL

Abstract

We present a series of ground and space-based photometry and ground-based spectroscopy of the Superluminous Type IIn Supernova (SLSN IIn) ASASSN-14il, which shows evidence for strong interaction with pre-existing circumstellar material (CSM). Our observations constrain the speed of the supernova shock and ejecta, as well as the speed, mass, and extent of the CSM that was ejected off the SN immediately preceding eruption. In our spectra, we measure the maximum speed of the CSM to be 176 km s−1 , being following by a 1600 km s−1 shock and 7065 km s−1 ejecta, by fitting and analyzing statistical distributions to the components of Hα emission. Our spectra reveal progressive blueshifting of the intermediate-width Hα emission from dust within the SN ejecta. During the 11 years before its death, we calculate that ASASSN-14il experienced extreme mass loss on the order of 1 M yr−1 , imparting 4.03×1048 erg of kinetic energy to the CSM. Integrating its light curve over the first 120 days, we found that ASASSN-14il radiated at least E = 5.74 × 1050erg in visual light alone, giving a lower limit to the total radiated energy.