A hyperspectral view of Cassiopeia A

We used the imaging Fourier transform spectrometer SpectromStre Imageur de l'Observatoire du Mont-M,gantic (SpIOMM) to obtain hyperspectral cubes of the young supernova remnant Cassiopeia A (Cas A). The cubes contain over 5000 spatially resolved spectra covering the spectral range 6480-7050 . We first investigate the slow-moving N-rich quasi-stationary flocculi by measuring their radial velocity as well as the [N ii] lambda 6583/H alpha ratio. No correlation between their radial velocity and [N ii] lambda 6583/H alpha ratio with their location has been found. We used multi-epoch observations from the Hubble Space Telescope to create a proper motion map, showing the displacement of several filaments over the most part of Cas A. Combining data from SpIOMM and Hubble, we re-evaluate the distance to Cas A and obtained 3.33 +/- A 0.10 kpc, which is in good agreement with previous estimates. Finally, we obtain a three-dimensional spatial view of the [S ii] lambda lambda 6716, 6731 emissions showing their location, expansion velocity and the [S ii] doublet line ratio for multiple locations in the remnant. The velocity asymmetry reported by previous analyses is clearly visible. Also, the [S ii] doublet ratio (with a mean value of 0.5 +/- A 0.2) indicates a very high and variable electronic density throughout the remnant.