Serendipitous detection of the dusty Type IIL SN 1980K with JWST /MIRI

We present mid-infrared (mid-IR) imaging of the Type IIL supernova (SN) 1980K with the JWST more than 40 yr post-explosion. SN 1980K, located in the nearby ( D ≈7 Mpc) 'SN factory' galaxy NGC 6946, was serendipitously captured in JWST /MIRI images taken of the field of SN 2004et in the same galaxy. SN 1980K serves as a promising candidate for studying the transitional phase between young SNe and older SN remnants and also provides a great opportunity to investigate its the close environment. SN 1980K can be identified as a clear and bright point source in all eight MIRI filters from F 560 W up to F 2550 W . We fit analytical dust models to the mid-IR spectral energy distribution that reveal a large amount ( M d ≈0.002 M ⊙) of Si-dominated dust at T dust ≈150 K (accompanied by a hotter dust/gas component), and also computed numerical SED dust models. Radiative transfer modelling of a late-time optical spectrum obtained recently with Keck discloses that an even larger ( ∼0.24-0.58 M ⊙) amount of dust is needed in order for selectiv e e xtinction to explain the asymmetric line profile shapes observed in SN 1980K. As a conclusion, with JWST , we may see i) pre-existing circumstellar dust heated collisionally (or, partly radiatively), analogous to the equatorial ring of SN 1987A, or ii) the mid-IR component of the presumed newly-formed dust, accompanied by much more colder dust present in the ejecta (as suggested by the late-time the optical spectra).