We report far-infrared and submillimeter observations of supernova 1987A, the star whose explosion was observed on 23 February 1987 in the Large Magellanic Cloud, a galaxy located 160,000 light years away. The observations reveal the presence of a population of cold dust grains radiating with a temperature of about 17 to 23 kelvin at a rate of about 220 times the luminosity of the Sun. The intensity and spectral energy distribution of the emission suggest a dust mass of about 0.4 to 0.7 times the mass of the Sun. The radiation must originate from the supernova ejecta and requires the efficient precipitation of all refractory material into dust. Our observations imply that supernovae can produce the large dust masses detected in young galaxies at very high redshifts.

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We searched the Spitzer Space Telescope data archive for Galactic planetary nebulae (PNe), that show the characteristic 17.4 and 18.9 µm features due to C 60 , also known as buckminsterfullerene. Out of 338 objects with Spitzer/IRS data, we found eleven C 60 -containing PNe, six of which (Hen2-68, IC2501, K3-62, M1-6, M1-9, and SaSt2-3) are new detections, not known to contain C 60 prior to this work. The strongest 17.4 and 18.9 µm C 60 features are seen in Tc 1 and SaSt 2-3, and these two sources also prominently show the C 60 resonances at 7.0 and 8.5 µm. In the other nine sources, the 7.0 and 8.5 µm features due to C 60 are much weaker. We analyzed the spectra, along with ancillary data, using the photo-ionization code CLOUDY to establish the atomic line fluxes, and determine the properties of the radiation field, as set by the effective temperature of the central star. In addition, we measured the infrared spectral features due to dust grains. We find that the Polycyclic Aromatic Hydrocarbon (PAH) profile over 6-9 µm in these C 60 -bearing carbon-rich PNe is of the more chemically-processed class A. The intensity ratio of 3.3 µm to 11.3 µm PAH indicates that the number of C-atoms per PAH in C 60 -containing PNe is small compared to that in non-C 60 PNe. The Spitzer spectra also show broad dust features around 11 and 30 µm. Analysis of the 30-µm feature shows that it is strongly correlated with the continuum, and we propose that a single carbon-based carrier is responsible for both the continuum and the feature. The strength of the 11-µm feature is correlated to the temperature of the dust, suggesting that it is at least partially due to a solid-state carrier. The chemical abundances of C 60 -containing PNe can be explained by AGB nucleosynthesis models for initially 1.5-2.5 M ⊙ stars with Z=0.004. We plotted the locations of C 60 -containing PNe on a face-on map of the Milky Way and we found that most of these PNe are outside the solar circle, consistent with low metallicity values. Their metallicity suggests that the progenitors are an older population.

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SN 2010jl was an extremely bright, Type IIn SNe which showed a significant IR excess no later than 90 days after explosion. We have obtained Spitzer 3.6 and 4.5 µm and JHK observations of SN 2010jl ∼90 days post explosion. Little to no reddening in the host galaxy indicated that the circumstellar material lost from the progenitor must lie in a torus inclined out of the plane of the sky. The likely cause of the high mid-IR flux is the reprocessing of the initial flash of the SN by pre-existing circumstellar dust. Using a 3D Monte Carlo Radiative Transfer code, we have estimated that between 0.03-0.35 M ⊙ of dust exists in a circumstellar torus around the SN located 6 × 10 17 cm away from the SN and inclined between 60-80 • to the plane of the sky. On day 90, we are only seeing the illumination of approximately 5% of this torus, and expect to see an elevated IR flux from this material up until day ∼ 450. It is likely this dust was created in an LBV-like mass loss event of more than 3 M ⊙ , which is large but consistent with other LBV progenitors such as η Carinae.