# A multispectral analysis of the northeastern shell of IC 443

## TL;DR

This study uses multispectral optical observations and shock modeling to analyze the physical conditions and spectral variations in the northeastern shell of supernova remnant IC 443, revealing diverse shock velocities, densities, and extinction properties.

## Contribution

It provides a detailed multispectral analysis combined with shock models to explain the spectral and morphological features of IC 443's northeastern shell, highlighting the need for mixed shock models.

## Key findings

- Shock velocities range from 20 to 150 km/s, with a prominent velocity at 75 km/s.
- Electron densities vary from 100 to 2500 cm$^{-3}$ across the region.
- Significant extinction variation with E(B-V) between 0.8 and 1.1.

## Abstract

We have carried out optical observations of the north-eastern part of the supernova remnant IC 443 using the CFHT imaging spectrograph SITELLE. The observations consist of three multispectral cubes covering an 11$^{\prime}$ $\times$11$^{\prime}$ area allowing the investigation of both the spatial and spectral variation of 9 emission lines : [OII] $\lambda\lambda$3726+3729, [OIII] $\lambda\lambda$4959,5007, H$\beta$, H$\alpha$, [NII] $\lambda\lambda$6548,6583 and [SII] $\lambda\lambda$6716,6731. Extinction measurement from the H$\alpha$ / H$\beta$ ratio shows significant variation across the observed region with E(B-V) = 0.8-1.1. Electron density measurements using [SII] lines indicate densities ranging from 100 up to 2500 cm$^{-3}$. Models computed with the shock modelling code MAPPINGS are presented and compared with the observations. A combination of complete shock model and truncated ones are required in order to explain the observed spectrum. The shock velocities found in IC 443 are between 20 and 150 km/s with 75 km/s being the most prominent velocity. The pre-shock number density varies from 20 to 60 cm$^{-3}$. A single set of abundances close to solar values combined with varying shock parameters (shock velocity, pre-shock density and shock age) are sufficient to explain to great variation of lines intensities observed in IC 443. Despite the relatively modest spectral resolution of the data (R$\sim 1500$ at H$\alpha$), we clearly separate the red and blue velocity components of the expanding nebula, which show significant morphological differences.