Revised Distances to 21 Supernova Remnants

TL;DR

This study revises the distances to 21 supernova remnants using HI and CO line observations, significantly impacting their physical property estimates and improving our understanding of their characteristics.

Contribution

It provides updated, more accurate distances for 21 SNRs based on new observational evidence and improved rotation curve analysis, enhancing previous measurements.

Findings

Revised distances for 10 SNRs based on new data.

Updated distances for 11 SNRs using an improved rotation curve.

Mean distance change of approximately 25%, or 1.5 kpc.

Abstract

We carry out a comprehensive study of HI 21 cm line observations and $^{13}$CO line observations of 21 supernova remnants (SNRs). The aim of the study is to search for HI absorption features to obtain kinematic distances in a consistent manner. The 21 SNRs are in the region of sky covered by the Very Large Array Galactic Plane Survey (HI 21 cm observations) and Galactic Ring Survey ($^{13}$CO line observations). We obtain revised distances for 10 SNRs based on new evidence in the HI and $^{13}$CO observations. We revise distances for the other 11 SNRs based on an updated rotation curve and new error analysis. The mean change in distance for the 21 SNRs is $\simeq25\%$, i.e. change of 1.5 kpc compared to a mean distance for the sample of 6.4 kpc. This has a significant impact on interpretation of the physical state of these SNRs. For example, using a Sedov model, age and explosion energy scale as the square of distance, and inferred ISM density scales as distance.