CO observations of SNR IC 443

TL;DR

This study provides high-resolution 13CO mapping of SNR IC 443, analyzing its interaction with molecular clouds through multi-wavelength comparisons and a new model explaining shock coexistence and gas dissociation.

Contribution

It introduces the first large-scale high-resolution 13CO mapping of IC 443 and proposes a new model for shock interactions in the central clump B region.

Findings

Identified complex gas motions in shocked regions.

Established relationship between shock velocity and molecular gas dissociation.

Derived optical depth of 12CO using 13CO spectra.

Abstract

We present our 12CO and 13CO mapping observations of SNR IC 443, interacting with molecular clouds. It is the first large scale high resolution 13CO mapping observation in the surrounding region. The morphologies of IC 443 in 12CO and 13CO are compared with the optical, infrared, Spitzer far-infrared, X-ray, and neutral atomic gas (HI). We also make comparison and analysis in the kinemics, using the date-cubes of 12CO, 13CO and HI, to help distinguish the complicated gas motions in the shocked regions. Based on the work of Wang & Scoville (1992), we present a new model to explain the origin of coexistence of shocks with different speeds in a rather small region at the central clump B. We test this new model via analyzing the HI and CO distributions in both velocity and space domains. We also establish the relationship between the dissociation rate of the shocked molecular gas and the shock velocity in this region. Finally, we derive the optical depth of 12CO with the 13CO spectra in clump B, and discuss the validity of the assumption of optically thin emission for the shocked 12CO.