Optical and H i observations of IC 443 and G189.6 + 3.3 in a complex environment

Abstract

The supernova remnant (SNR) IC 443 is one of the best-studied Galactic SNRs at many wavelengths. It is interacting with a very complex environment, including the SNR G189.6 + 3.3 and H ii regions. In this paper, we report on observations of IC 443 and G189.6 + 3.3 using 1.5- and 1-m telescopes to better understand the nature of these SNRs in the optical band. We obtain H$\alpha$ images showing both filamentary and diffuse structures, and long-slit spectra from many locations, with Balmer and forbidden lines detected for IC 443 and G189.6 + 3.3. The [S ii]/ H$\alpha$ ratios confirm the SNR nature of G189.6 + 3.3. The ranges of our estimated electron density and pre-shock cloud density clearly indicate the complex structure surrounding IC 443 and G189.6 + 3.3. We also investigate the archival H i data and newly find some shell-like distributions of H i that are possibly associated with G189.6 $+$ 3.3.