A multispectral analysis of the northeastern shell of IC 443

Abstract

Abstract We have carried out optical observations of the northeastern part of the supernova remnant IC 443 using the Canada–France–Hawaii Telescope imaging spectrograph SITELLE. The observations consist of three multispectral cubes covering an 11′ × 11′ area allowing the investigation of both the spatial and spectral variation of nine emission lines:  [O ii] λλ3726 + 3729,  [O iii] λλ4959, 5007,  H β,  H α,  [N ii] λλ6548, 6583, and  [S ii] λλ6716, 6731. Extinction measurement from the  H α/ H β shows significant variation across the observed region with E(B − V) = 0.8–1.1. Electron density measurements using  [S ii] 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 is required in order to explain the observed spectrum. The shock velocities found in IC 443 are between 20 and 150  km s−1, with 75  km s−1 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) is sufficient to explain the great variation of line intensities observed in IC 443. Despite the relatively modest spectral resolution of the data (R ∼ 1500 at  H α), we clearly separate the red and blue velocity components of the expanding nebula, which show significant morphological differences.