The timing and location of dust formation in the remnant of SN 1987A

Abstract

The discovery with the Herschel Space Observatory of bright far infrared and submm emission from the ejecta of the core collapse supernova SN 1987A has been interpreted as indicating the presence of some 0.4-0.7 M of dust. We have constructed radiative transfer models of the ejecta to fit optical to far-infrared observations from the literature at epochs between 615 days and 24 years after the explosion, to determine when and where this unexpectedly large amount of dust formed.We find that the observations by day 1153 are consistent with the presence of 3×10 −3 M of dust. Although this is a larger amount than has previously been considered possible at this epoch, it is still very small compared to the amount present in the remnant after 24 years, and significantly higher dust masses at the earlier epochs are firmly ruled out by the observations, indicating that the majority of the dust must have formed at very late times. By 8515-9200 days after the explosion, 0.6-0.8 M of dust is present, and dust grains with radii greater than 2 µm are required to obtain a fit to the observed SED. This suggests that the dust mass increase at late times was caused by accretion onto and coagulation of the dust grains formed at earlier epochs.These findings provide further confirmation that core collapse supernovae can create large quantities of dust, and indicate that the reason for small dust masses being estimated in many cases is that the vast majority of the dust forms long after most supernovae have been detectable at mid-infrared wavelengths.

Condensation of dust in the ejecta of Type II-P supernovae

“…Total modelled dust masses versus post-explosion time for the various SN cases considered in this study and dust masses derived from mid-IR data for a sample of Type II-P SNe-SN1987A (Wooden et al 1993;Ercolano et al 2007), SN1999em (Elmhamdi et al 2003), SN2003gd (Sugerman et al 2006;Meikle et al 2007), SN2003J (Szalai & Vinkó 2013), SN2004dj (Szalai et al 2011;Meikle et al 2011 well with the latest submm dust masses derived from Herschel and ALMA data for SN1987A and other SNRs. The trend of a gradual growth of dust grains over ∼3−5 years is in contrast with recent radiative transfer study of SN1987A by Wesson et al (2015), who conclude the major growth of dust grains has taken place between day 1200 and day 9200, and that the grains are very large (a ∼ 3−5 µm). They argue that growth by atom accretion on the grain surface is not effective enough to form such large grains and propose coagulation instead.…”

Measuring the dust content and formation in SN 1987A using detailed radiative transfer modelling

“…We have run initial test simulations for SN 1987A at the most recent epoch in which we vary 5 different parameters (luminosity, dust mass, silicate fraction, clumpiness and mean grain size). Preliminary results seem to indicate the need for large, micron-sized dust grains, and a relatively large dust mass (> 0.5 M ), in agreement with Wesson et al (2015).…”

“…Sluder et al (2016) presented a detailed analysis of dust formation in SN 1987A based on the so-called molecular nucleation theory, which tracks the abundance of each molecular species with a nonequilibrium chemical reaction network, and which includes effects such as coagulation, grain charging, evaporation, accretion, and chemical weathering. They find a grain size distribution with a power law that is steeper than the one inferred by the studies of Wesson et al (2015) and Dwek & Arendt (2015). Moreover, Sluder et al (2016) predict a radically different dust composition compared to the one assumed by most previous studies.…”

“…Recent work by various teams has come to drastically different conclusions. Wesson et al (2015) and Bevan & Barlow (2016) used radiation transfer calculations to simulate the evolution of the observed spectral energy distribution (SED) and emission line blueshifting of SN 1987A. According to their analyses, the dust mass increases as a power law in time, and 97.5% of the dust mass formed after 1300 days.…”

Akari Near-Infrared Spectroscopy of the Extended Green Object G318.05+0.09: Detection of Co Fundamental Ro-Vibrational Emission

“…Cas A is a SNR of 340 years old and it is the only SNR in which both high-J rotational and ro-vibrational lines of warm CO gas have been detected (Rho et al 2012;Wallström et al 2013). Processing and evolution of dust and gas in SN ejecta after the explosion, in particular the effects of the reverse shock, have been becoming an important issue for the understanding of the net dust formation yield in SNe (Bianchi & Schneider 2007;Nozawa et al 2007Nozawa et al , 2010Nath et al 2008;Silvia et al 2010aSilvia et al , 2012Gall et al 2014;Dwek & Arendt 2015;Wesson et al 2015;Biscaro & Cherchneff 2016). Biscaro & Cherchneff (2014) show that dust and molecules in ejecta clumps are destroyed by the reverse shock, whereas CO gas can reform in the post-reverse shock gas, but dust clusters do not.…”