Mike

Using a recently developed 3D Monte Carlo dust line-scattering and
absorption code, Bevan & Barlow (2016, MNRAS) have modeled the red-blue
line asymmetries in the late-time H$alpha$ and [O {sc i}] spectra of SN
1987A caued by the preferential absorption by internal dust particles of
redshifted photons from the far side of the ejecta. They found dust masses
that grew from $leq10^{-3}$ M$_{odot}$ on day 714 to $geq$0.10
M$_{odot}$ by day 3604, a trend that agrees with the day 615-9200 SED
modeling results of Wesson et al. (2015) for SN 1987A, for which Herschel
and ALMA observations indicate a dust mass of $sim$0.7 M$_{odot}$ by day
9200.

Similar red-blue emission line asymmetries are often observed in the
late-time optical spectra of other supernova ejecta and remnants. With the
aim of increasing the number of SNR dust mass determinations, we have
modeled the red-blue emission line asymmetries in the late-time optical
spectra of SN 1993J and SN 1980K published by Milisavljevic & Fesen
(2013), as well as modeling similar red-blue line asymmetries seen in the
integrated optical spectrum of Cas A published by Milisavljevic et al.
(2013). Depending on grain composition, clumped dust masses of 0.1-0.4
M$_{odot}$ are required to provide fits to the Year-31 H$alpha$ and [O
{sc i}] line profiles of SN 1980K, while fits to the Year-16 [O {sc ii}]
and [O {sc iii}] line profiles of SN 1993J require up to 0.18 M$_{odot}$
of clumped ejecta dust. For Cas A, the fits to its [O {sc i}], [O {sc
ii}] and [O {sc iii}] integrated line profiles require about 1
M$_{odot}$ of internal dust to be present.