Confined Circumstellar Material as a Dust Formation Site in Type II Supernovae

Some massive stars undergo episodic mass loss shortly before core-collapse, producing dense circumstellar material (CSM) in their immediate surroundings. If the supernova (SN) ejecta strongly interacts with such CSM, narrow emission lines appear in the spectrum, classifying the event as Type IIn. In these cases, efficient radiative cooling forms a cold, dense shell (CDS), providing ideal conditions for dust condensation. Infrared observations of several SNe IIn have indeed confirmed newly formed dust. Recent time-domain surveys, however, suggest that compact and dense CSM, often termed “confined CSM”, is also present around a broader class of Type II SN progenitors with hydrogen-rich envelopes, beyond the traditional Type IIn subclass. This raises the possibility that dust formation in dense CSM is more common among core-collapse SNe than previously thought. In this talk, I will demonstrate that CDS formation occurs robustly across a wide parameter space for confined CSM using numerical simulations based on the open-source code CHIPS. I will also discuss the resulting dust mass and infrared emission, as well as the potential contribution of this process to the galactic dust budget.