The Sigma-D relation for shell-like supernova remnants

A large fraction of Galactic supernova remnants, including a dozen shell-like remnants, can be associated with large molecular clouds or cloud complexes with well-determined distances. The Sigma-D relation for these shell-like remnants, derived using distances to the associated molecular clouds, shows substantially smaller scatter than previous relations and establishes a good distance scale for shell-like remnants from Type II events.