Thermonuclear explosions as Type II supernovae

TL;DR

This paper models a thermonuclear explosion in a binary system that mimics Type IIP supernovae, suggesting some observed SNe IIP could be misclassified thermonuclear events within a common envelope.

Contribution

It introduces a new scenario where thermonuclear explosions in binary systems can produce light curves similar to SNe IIP, challenging traditional classification methods.

Findings

Thermonuclear explosions can produce Type IIP-like light curves.

Five observed SNe IIP match the model's light curve.

Such explosions may be mistaken for core-collapse supernovae.

Abstract

We consider a binary stellar system, in which a low-mass, of 0.6 Msun, carbon-oxygen white dwarf (WD) mergers with a degenerate helium core of 0.4 Msun of a red giant. We analyse the outcome of a merger within a common envelope (CE). We predict the observational properties of the resulting transient. We find that the double detonation of the WD, being a pure thermonuclear explosion and embedded into the hydrogen-rich CE, has a light curve with the distinct plateau shape, i.e. looks like a supernova (SN) Type IIP, with a duration of about 40 days. We find five observed SNe IIP: SN 2004dy, SN 2005af, SN 2005hd, SN 2007aa, and SN 2008bu, that match the V-band light curve of our models. Hence, we show that a thermonuclear explosion within a CE might be mistakenly identified as a SN IIP, which are believed to be an outcome of a core-collapse neutrino-driven explosion of a massive star. We discuss a number of diagnostics, that may help to distinguish this kind of a thermonuclear explosion from a core-collapse SN.