Two Supernovae in NGC 4666: ASASSN-14lp and 2019yvr

Abstract

The results of photometric observations of two supernovae in NGC 4666, SN Ia ASASSN-14lp and SN Ib 2019yvr, as well as spectroscopic observations of SN 2019yvr, are presented. Light curves have been constructed, and their main parameters have been derived. Supernova ASASSN-14lp is a fairly typical Type Ia object with low rate of brightness decline and large interstellar extinction. Using the dependence of the maximum luminosity of SNe Ia on the light curve parameters, an estimate of the distance to the galaxy NGC 4666 has been obtained. The spectrum of SN 2019yvr near maximum light, its peak luminosity, and the shapes of the light curves during the first 90 days after maximum revealed characteristics of a typical Type Ib supernova, with interstellar extinction exceeding that of ASASSN-14lp. A decrease in the rate of brightness decline at a phase of approximately 90 days has been detected. Light curve modeling was performed using the STELLA code, and the physical parameters of the optimal model were determined. It is shown that the agreement between the model and observations breaks down after \({\sim}\)40 days post-maximum; to explain this divergence, a model with an extra energy source due to the spin-down of the magnetar formed in the explosion has been proposed.