3D distribution of metals in nova shells

A nova eruption in a cataclysmic variable (CV) is a thermonuclear explosion on the surface of the white dwarf primary once it has accreted a critical mass from its late-type companion. During the nova eruption, material is ejected into the interstellar medium, forming an expanding shell around the CV which can be observed once its angular size is sufficiently large to be resolved and separated from the inner binary. The spectra of such shells are usually dominated by various emission lines including Hydrogen, Helium and forbidden metal lines. We have used the Multi Unit Spectroscopic Explorer (MUSE) to observe several such nova shells. For any of the various emission lines present in the spectra, the radial velocity distribution at each spaxel relates directly to the spatial distribution in z-direction. Using Gaia distances, also the angular distribution can be transformed into physical x,y-coordinates. Thus, full 3D-images of the expanding shell can be constructed for the various emission lines. We find significant differences in the distribution of H or He and the forbidden metal lines. Such discriminating 3D-structures of the shells provide information on the mechanisms and processes during the nova eruption.