Issue |
A&A
Volume 395, Number 1, November III 2002
|
|
---|---|---|
Page(s) | 189 - 200 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20021271 | |
Published online | 29 October 2002 |
Infrared emission towards SN 1987A, 11 years after outburst: Properties of the circumstellar dust
Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69115 Heidelberg, Germany
Corresponding author: Jg. Fischera, Joerg.Fischera@mpi-hd.mpg.de
Received:
30
April
2002
Accepted:
28
August
2002
Detailed models are presented for the late epoch mid infrared (MIR) emission
from collisionally heated grains in the shocked circumstellar gas around SN 1987A.
Thermal dust emission from a region of moderate
density interior to the thick inner ring seen with the Hubble Space Telescope (HST)
is found to be a natural explanation for the MIR spectral energy distribution
measured by ISOCAM. The MIR-spectrum can be reproduced by a mixture of silicate-iron
or silicate-graphite grains or by a composition of pure graphite grains. A composition
of pure iron grains on the other hand can be excluded and a pure silicate composition
does not seem to be very likely.
The dust-to-gas ratio in the interaction zone is ~, an order of magnitude
lower than estimates for dust abundances in the winds of red supergiant (RSG) stars in the LMC.
This low dust abundance can be accounted for by a combination of
evaporation through the UV-flash from the supernova outburst and subsequent
sputtering in the shocked gas.
For this explanation to hold, dust in the pre-supernova circumstellar medium (CSM)
would have to have been predominantly composed of grains other than graphite, with
a maximum size smaller than ~
.
Key words: stars: supernovae: individual: SN 1987A / infrared: ISM / stars: circumstellar matter
© ESO, 2002
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