SN 2020sck: Deflagration in a Carbon-Oxygen White Dwarf

Abstract

We present optical UBVRI photometry and low-to-medium resolution spectroscopic observations of type Iax supernova SN 2020sck spanning −5.5 days to +67 days from maximum light in the B-band. From the photometric analysis we find ΔmB(15) = 2.03 ± 0.05 mag and MB = −17.81 ± 0.22 mag. Radiation diffusion model fit to the quasi-bolometric light curve indicates 0.13 ± 0.02 M⊙ of 56Ni and 0.34 M⊙ of ejecta are synthesized in the explosion. Comparing the observed quasi-bolometric light curve with the angle-averaged bolometric light curve of a three-dimensional pure deflagration explosion of Mch carbon-oxygen white dwarf, we find agreement with a model in which 0.16 M⊙ of 56Ni and 0.37 M⊙ of ejecta is formed. By comparing the +1.4 days spectrum of SN 2020sck with synthetic spectrum generated using SYN++, we find absorption features due to C ii, C iii, and O i. These are unburned materials in the explosion and indicate a C–O white dwarf. One-dimensional radiative transfer modeling of the spectra with TARDIS shows higher density in the ejecta near the photosphere and a steep decrease in the outer layers with an ejecta composition dominated mostly by C, O, Si, Fe, and Ni. The star-formation rate of the host galaxy computed from the luminosity of the Hα (λ6563) line is 0.09 M⊙ yr−1, indicating a relatively young stellar environment.