2023/02/09 by Dickinson, Danielle, Smith, Nathan, Andrews, Jennifer E. +3 · 2 citations
#FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Solar and Stellar Astrophysics (astro-ph.SR)
paper · doi:10.48550/arxiv.2302.04958
We present a series of ground-based photometry and spectroscopy of the superluminous Type IIn supernova (SN) ASASSN-15ua, which shows evidence for strong interaction with pre-existing dense circumstellar material (CSM). Our observations constrain the speed, mass-loss rate, and extent of the progenitor wind shortly before explosion. A narrow P Cygni absorption component reveals a progenitor wind speed of ∼100 km s-1. As observed in previous SNe IIn, the intermediate-width Hα emission became more asymmetric and blueshifted over time, suggesting either asymmetric CSM, an asymmetric explosion, or increasing selective extinction from dust within the post-shock shell or SN ejecta. Based on the CSM radius and speed, we find that the progenitor suffered extreme eruptive mass loss with a rate of 0.1-1 M_\odot yr-1 during the ∼12 years immediately before the death of the star that imparted ∼ 1048 erg of kinetic energy to the CSM. Integrating its V-band light curve over the first 170 days after discovery, we find that ASASSN-15ua radiated at least 3×1050 erg in visual light alone, giving a lower limit to the total radiated energy that may have approached 1051 erg. ASASSN-15ua exhibits many similarities to two well-studied superluminous SNe IIn: SN 2006tf and SN 2010jl. Based on a detailed comparison of these three, we find that ASASSN-15ua falls in between these two events in a wide variety of observed properties and derived physical parameters, illustrating a continuum of behavior across superluminous SNe IIn.