Point-symmetry in SNR G1.9+0.3: A Supernova that Destroyed its Planetary Nebula Progenitor

Abstract

I analyze a new X-ray image of the youngest supernova remnant (SNR) in the Galaxy, which is the type Ia SNR G1.9+0.3, and reveal a very clear point-symmetrical structure. Since explosion models of type Ia supernovae (SNe Ia) do not form such morphologies, the point-symmetrical morphology must come from the circumstellar material (CSM) into which the ejecta expands. The large-scale point-symmetry that I identify and the known substantial deceleration of the ejecta of SNR G1.9+0.3 suggest a relatively massive CSM of ≳1M _⊙. I argue that the most likely explanation is the explosion of this SN Ia into a planetary nebula. The scenario that predicts a large fraction of SN Ia inside PNe (SNIPs) is the core degenerate scenario. Other SN Ia scenarios might lead to only a very small fraction of SNIPs or none at all.