On the origin of two-shell supernova remnants

TL;DR

This paper proposes that the proper motion of massive stars leads to asymmetric supernova remnants with two shells, explaining observed structures like the Cygnus Loop.

Contribution

It introduces a new explanation for two-shell supernova remnants based on stellar motion affecting explosion symmetry.

Findings

Proper motion causes asymmetry in supernova remnants.

Two-shell structures can result from off-center explosions.

Explains specific remnants like Cygnus Loop.

Abstract

The proper motion of massive stars could cause them to explode far from the geometric centers of their wind-driven bubbles and thereby could affect the symmetry of the resulting diffuse supernova remnants. We use this fact to explain the origin of SNRs consisting of two partially overlapping shells (e.g. Cygnus Loop, 3C 400.2, etc.).