JWST Spectra Indicate a Large Mass of Postshock Dust Formed by SN 2010jl

We present new James Webb Space Telescope (JWST) mid-infrared (MIR) spectra and ground-based optical spectra of the lingering source at the position of supernova (SN) 2010jl, which was a relatively nearby superluminous Type IIn supernova (SLSN IIn) having strong interaction with circumstellar material (CSM). Early-time data showed evidence of dust, interpreted as either preexisting CSM dust, or as newly formed dust in the SN ejecta and postshock region. At 13 yr post explosion, JWST reveals a strong MIR excess from warm dust, with broad features at 10–15 μm. Our analysis reveals a minimum dust mass of >0.11 M_⊙, and a more likely value of 0.2 M_⊙ or more because the dust is optically thick. This is among the largest masses of SN-produced dust yet measured without far-IR/submillimeter data, and greatly exceeds SN 2010jl’s dust mass inferred around 2–3 yr postexplosion. Ground-based optical spectra confirm the presence of a young massive cluster at the SN position and confirm that blueshifted line profiles persisting until the latest epochs arise from dust formed in the postshock region. The warmest dust emitting in the MIR is likely to be the same post-shock dust causing the blueshift. The JWST spectrum also reveals silicate absorption, which may arise from cool SN ejecta dust along the line of sight to the receding shock. The large mass of postshock dust in SN 2010jl suggests that strong CSM interaction promotes efficient dust production, where the new postshock dust will survive. If strongly interacting SNe are common in the early Universe, this may contribute significantly to dust seen in infant galaxies.