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.
@article{arxiv.2401.10401,
title = {Thermonuclear explosions as Type II supernovae},
author = {Alexandra Kozyreva and Javier Moran-Fraile and Alexander Holas and Vincent A. Bronner and Friedrich K. Roepke and Nikolay Pavlyuk and Alexey Mironov and Dmitriy Tsvetkov},
journal= {arXiv preprint arXiv:2401.10401},
year = {2024}
}