Observational Predictions for Sub-Chandrasekhar Mass Explosions: Further Evidence for Multiple Progenitor Systems for Type Ia Supernovae
Skip to main content
eScholarship
Open Access Publications from the University of California

Observational Predictions for Sub-Chandrasekhar Mass Explosions: Further Evidence for Multiple Progenitor Systems for Type Ia Supernovae

  • Author(s): Polin, A
  • Nugent, P
  • Kasen, D
  • et al.
Abstract

We present a numerical parameter survey of 1-D sub-Chandrasekhar mass white dwarf explosions. Carbon-oxygen white dwarfs accreting a helium shell have the potential to explode in the sub-Chandrasekhar mass regime. Previous studies have shown how the ignition of a helium shell can either directly ignite the white dwarf at the core-shell interface or propagate a shock wave into the center of the core causing a shock driven central ignition. We examine the explosions of white dwarfs from 0.6 - 1.2 $M_{\odot}$ with Helium shells of 0.01 $M_{\odot}$, 0.05 $M_{\odot}$ and 0.08$M_{\odot}$. Distinct observational signatures of sub-Chandrasekhar mass white dwarf explosions are predicted for two categories of shell size. Thicker-shell models show an excess of flux combined with red colors for the first few days after explosion. The flux excess is caused by the presence of radioactive material in the ashes of the helium shell, and the red colors are due to these ashes creating significant line blanketing in the UV through the blue portion of the spectrum. Models with thin helium shells reproduce several typical Type Ia supernova signatures. We identify a relationship between Si II velocity and luminosity which, for the first time, identifies a sub-class of observed supernovae that are consistent with these models. This sub-class is further delineated by the absence of carbon in their atmospheres. Finally, we suggest that the proposed difference in the ratio of selective to total extinction between the high velocity and normal velocity Type Ia supernovae is not due to differences in the properties of the dust around these events, but is rather an artifact of applying a single extinction correction to two populations of supernovae which likely have different intrinsic colors.

Main Content
Current View