The luminous Type IIn SN 2010jl shows strong signs of interaction between the SN ejecta and dense circumstellar material. Dust may be present in the unshocked ejecta; the cool, dense shell (CDS) between the shocks in the interaction region; or in the circumstellar medium (CSM). We present and model new optical and infrared photometry and spectroscopy of SN 2010jl from 82 to 1367 days since explosion. We evaluate the photometric and spectroscopic evolution using the radiative transfer codes MOCASSIN and DAMOCLES, respectively. We propose an interaction scenario and investigate the resulting dust formation scenarios and dust masses. We find that SN 2010jl has been continuously forming dust based on the evolution of its infrared emission and optical spectra. There is evidence for preexisting dust in the CSM as well as new dust formation in the CDS and/or ejecta. We estimate that 0.005-0.01 M e of predominantly carbon dust grains has formed in SN 2010jl by ∼1400 days post-outburst. Unified Astronomy Thesaurus concepts: Core-collapse supernovae (304); Type II supernovae (1731); Circumstellar dust (236); Dust continuum emission (412); Dust nebulae (413); Astronomical models (86); Radiative transfer (1335); Extinction (505); Circumstellar shells (242); Dust shells (414)

The large quantities of dust that have been found in a number of high redshift galaxies have led to suggestions that core-collapse supernovae (CCSNe) are the main sources of their dust and have motivated the measurement of the dust masses formed by local CCSNe. For Cassiopeia A, an oxygen-rich remnant of a Type IIb CCSN, a dust mass of 0.6-1.1 M⊙ has already been determined by two different methods, namely (a) from its far-infrared spectral energy distribution and (b) from analysis of the red-blue emission line asymmetries in its integrated optical spectrum. We present a third, independent, method for determining the mass of dust contained within Cas A. This compares the relative fluxes measured in similar apertures from [O iii] far-infrared and visual-region emission lines, taking into account foreground dust extinction, in order to determine internal dust optical depths, from which corresponding dust masses can be obtained. Using this method we determine a dust mass within Cas A of at least 0.99$^{+0.10}_{-0.09}$ M⊙.

Modelling the red-blue asymmetries seen in the broad emission lines of core-collapse supernovae (CCSNe) is a powerful technique to quantify total dust mass formed in the ejecta at late times (>5 years after outburst) when ejecta dust temperatures become too low to be detected by mid-IR instruments. Following our success in using the Monte Carlo radiative transfer code damocles to measure the dust mass evolution in SN 1987A and other CCSNe, we present the most comprehensive sample of dust mass measurements yet made with damocles, for CCSNe aged between four and sixty years after outburst. Our sample comprises of multi-epoch late-time optical spectra taken with the Gemini GMOS and VLT X-Shooter spectrographs, supplemented by archival spectra. For the fourteen CCSNe that we have modelled, we confirm a dust mass growth with time that can be fit by a sigmoid curve which is found to saturate beyond an age of ∼30 years, at a mass of 0.23$^{+0.17}_{-0.12}$ M⊙. An expanded sample including dust masses found in the literature for a further eleven CCSNe and six CCSN remnants, the dust mass at saturation is found to be 0.42$^{+0.09}_{-0.05}$ M⊙. Uncertainty limits for our dust masses were determined from a Bayesian analysis using the affine invariant Markov Chain Monte Carlo ensemble sampler emcee with damocles. The best-fitting line profile models for our sample all required grain radii between 0.1 and 0.5 μm. Our results are consistent with CCSNe forming enough dust in their ejecta to significantly contribute to the dust budget of the Universe.

We present multiband optical photometric and spectroscopic observations of an unusual Type II supernova, SN 2018hfm, which exploded in the nearby (d ≈ 34.67 Mpc) dwarf galaxy PGC 1297331 with a very low star formation rate (0.0270 M⊙ yr−1) and a subsolar metallicity environment (∼0.5 Z⊙). The V-band light curve of SN 2018hfm reaches a peak with value of −18.69 ± 0.64 mag, followed by a fast decline (4.42 ± 0.13 mag (100 d)−1). After about 50 d, it is found to experience a large flux drop (∼3.0 mag in V), and then enters into an unusually faint tail, which indicates a relatively small amount of 56Ni synthesized during the explosion. From the bolometric light curve, SN 2018hfm is estimated to have low ejecta mass (∼1.3 M⊙) and low explosion energy (∼1050 erg) compared with typical SNe II. The photospheric spectra of SN 2018hfm are similar to those of other SNe II, with P Cygni profiles of the Balmer series and metal lines, while at late phases the spectra are characterized by box-like profiles of H α emission, suggesting significant interaction between the SN ejecta and circumstellar matter. These box-like emission features are found to show increasing asymmetry with time, with the red-side component becoming gradually weaker, indicating that dust is continuously formed in the ejecta. Based on the dust-estimation tool damocles, we find that the dust increases from ∼10−6 M⊙ to 10−4–10−3 M⊙ between +66.7 d and +389.4 d after explosion.

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