Revisiting the formation of molecules and dust in core collapse supernovae

Context. Core-collapse Supernovae (CCSNe) classed as Type II contribute to the chemical enrichment of galaxies through explosion. Their role as dust producers in the high-redshift Universe may be of paramount importance. However, the type and amount of dust they synthesise following the outburst are still a matter of debate and their formation processes also remain unclear. Aims. We aim to identify and understand the chemical processes at play in the dust formation scenario. We also derive mass yields for molecules and dust clusters at late post-explosion time. Methods. We revisited existing models by improving on the physics and chemistry of the supernova ejecta. We identified and evaluated new chemical species and pathways underpinning the formation of dust clusters. We applied a unique exhaustive chemical network to the entire ejecta of a SN with a 15 M ⊙ progenitor. We tested this new chemistry for various gas conditions in the ejecta, and derived mass yields for molecules and dust clusters. Results. We obtained the molecular component of the ejecta up to 11 years after explosion. The most abundant species are, in order of decreasing masses, O 2 , CO, SiS, SiO, CO 2 , SO 2 , CaS, N 2 , and CS. Atomic oxygen is quickly depleted after 300 days post-explosion in a large part of the oxygen core owing to the efficient synthesis of O 2 . Caution should then be exercised in the use of atomic oxygen masses as a supernova diagnostic. We identified molecules that are tracers of high-density clumps. As for dust clusters, we find the composition is dominated by silicates and silica, along with carbon dust, but with modest amounts of alumina. Pure metal clusters and metal sulphide and oxide clusters have negligible masses. High-density gas favours the formation of carbon clusters in the outer ejecta region whereas low temperatures hamper the formation of silicates in the oxygen core. These results are in good agreement with existing astronomical data and recent observations with the James Webb Space Telescope (JWST). They highlight the importance of chemistry in the derivation of dust budgets from supernovae.