Extraordinary Supernova iPTF14hls: An Attempt at Interpretation

Abstract

We show that the Hα luminosity and the Thomson optical depth of supernova iPTF14hls on day 600 after its discovery make it possible to estimate the envelope age at this stage, which turns out to be ~1000 days. A model that suggests the explosion of a massive star with a radius of ~2 × 10¹³ cm 450 days before the discovery is proposed. In the optimal model the ejecta mass is 30 M_ʘ with a kinetic energy of 8 × 10⁵¹ erg. The energy source at the main luminosity stage is presumably associated with the relativistic bipolar outflows produced by disk accretion onto a black hole. The [O I] 6300, 6364 Å doublet in the spectrum on day 600 is shown to be the result of emission from at least 1–3M_ʘ of oxygen in the central ejecta zone. The oxygen distribution is aspherical and can be represented both by two blue- and redshifted components (in the optically thin case) and by one blueshifted component in the case of optically thick lines at an oxygen filling factor of ~2 × 10⁻³.