The fraction of type Ia supernovae exploding inside planetary nebulae (SNIPs)

TL;DR

This study estimates that at least 20% of type Ia supernovae occur inside planetary nebulae, using multiple observational methods, and concludes that core degenerate and double degenerate scenarios dominate their origins.

Contribution

The paper provides the first multi-method estimate of the fraction of SNe Ia exploding inside planetary nebulae, supporting the dominance of core degenerate and double degenerate scenarios.

Findings

At least 20% of SNe Ia are SNIPs based on sodium absorption lines.

Hydrogen-rich CSM indicates a SNIP origin for some SNe Ia.

10-30% of SNR Ia show features consistent with SNIP origin.

Abstract

Using three independent directions we estimate that the fraction of type Ia supernovae (SNe Ia) exploding inside planetary nebulae (PNe), termed SNIPs,is at least ~20%. Our three directions are as follows. (i) Taking the variable sodium absorption lines in some SN Ia to originate in a massive circumstellar matter (CSM), as has been claimed recently, we use the results of Sternberg et al. (2014) to imply that > ~20% of SN Ia occur inside a PN (or a PN descendant), hence classify them as SNIPs. (ii) We next use results that show that whenever there are hydrogen lines in SN Ia the hydrogen mass in the CSM is large (> 1 M_Sun), hence the explosion is a SNIP. We make the simplest assumption that the probability for explosion is constant in time for up to about 10^5 yrs after the merger of the core with the white dwarf (WD) in the frame of the core-degenerate scenario. This results with at least few x10 of SNe Ia that may have a SNIP origin. (iii) We examine the X-ray morphologies of 13 well-resolved close-by SN remnants (SNRs) Ia and derive a crude upper limit, according to which 10-30% of all SNRs Ia possess opposite ear-like features, which we take as evidence of SNIP origin. Our results, together with several other recent results, lead us to conclude that the two scenarios most contributing to SNe Ia are the core degenerate and the double degenerate scenarios. Together these two account for >95% of all SNe Ia.