Although a number of models for the formation of dust in the ejecta of core-collapse supernovae (CCSNe) had predicted that between 0.1 and 1.0 Msun of dust could be formed per event, it was not until the 2009-2013 Herschel mission that direct observational evidence was obtained for the presence of such large masses of dust in several young supernova remnants, including Cas A, the Crab Nebula and SN 1987A. High angular resolution submillimetre observations of SN 1987A with ALMA subsequently confirmed that its cold dust emission originated from the inner expanding ejecta. The presence of dust in CCSN ejecta can also be diagnosed and quantified from red-blue asymmetries in their late-time optical emission line profiles. I will summarise current results for SN dust masses based on these methods.
The ALMA observations of the ejecta of SN 1987A also revealed strong CO and SiO rotational line emission. Broad CO line emission has also been detected from the reverse shock region of Cas A, while ArH+ (argonium) rotational lines were first detected by Herschel from the Crab Nebula. These molecular lines have opened up the possibility of measuring supernova isotope ratios for the first time.