Dust masses for SN 1980K, SN1993J and Cassiopeia A from red-blue emission line asymmetries

We present Monte Carlo line transfer models that investigate the effects of dust on the very late time emission line spectra of the core-collapse supernovae SN 1980K and SN 1993J and the young core collapse supernova remnant Cassiopeia A. Their blueshifted emission peaks, resulting from the removal by dust of redshifted photons emitted from the far sides of the remnants, and the presence of extended red emission wings are used to constrain dust compositions and radii and to determine the masses of dust in the remnants. We estimate dust masses of between 0.08 and 0.15M circle dot for SN1993J at year 16, 0.12 and 0.30M circle dot for SN1980K at year 30 and similar to 1.1 M circle dot for Cas A at year similar to 330. Our models for the strong oxygen forbidden lines of Cas A require the overall modelled profiles to be shifted to the red by between 700 and 1000 km s(-1), consistent with previous estimates for the shift of the dynamical centroid of this remnant.