Sn 2010lp—a Type Ia Supernova From a Violent Merger of Two Carbon-Oxygen White Dwarfs

SN 2010lp is a subluminous Type Ia supernova (SN Ia) with slowly evolving lightcurves. Moreover, it is the only subluminous SN Ia observed so far that shows narrow emission lines of [O i ] in late-time spectra, indicating unburned oxygen close to the center of the ejecta. Most explosion models for SNe Ia cannot explain the narrow [O i ] emission. Here, we present hydrodynamic explosion and radiative transfer calculations showing that the violent merger of two carbon–oxygen white dwarfs of 0.9 and 0.76 M ☉ adequately reproduces the early-time observables of SN 2010lp. Moreover, our model predicts oxygen close to the center of the explosion ejecta, a pre-requisite for narrow [O i ] emission in nebular spectra as observed in SN 2010lp.