H. L. Gomez, C. J. R. Clark, T. Nozawa, O. Krause, E. L. Gomez, M. Matsuura, M. J. Barlow, M. -A. Besel, L. Dunne, W. K. Gear, P. Hargrave, Th. Henning, R. J. Ivison, B. Sibthorpe, B. M. Swinyard, R. Wesson
The origin of interstellar dust in galaxies is poorly understood,
particularly the relative contributions from supernovae and the cool stellar
winds of low-intermediate mass stars. Here, we present Herschel PACS and SPIRE
photometry at 70-500um of the historical young supernova remnants: Kepler and
Tycho; both thought to be the remnants of Type Ia explosion events. We detect a
warm dust component in Kepler's remnant with T = 82K and mass 0.0031 M\odot;
this is spatially coincident with thermal X-ray emission optical knots and
filaments, consistent with the warm dust originating in the circumstellar
material swept up by the primary blast wave of the remnant. Similarly for
Tycho's remnant, we detect warm dust at 90K with mass 0.0086 M\odot. Comparing
the spatial distribution of the warm dust with X-rays from the ejecta and
swept-up medium, and Ha emission arising from the post-shock edge, we show that
the warm dust is swept up interstellar material. We find no evidence of a cool
(25-50 K) component of dust with mass \geq 0.07 M\odot as observed in
core-collapse remnants of massive stars. Neither the warm or cold dust
components detected here are spatially coincident with supernova ejecta
material. We compare the lack of observed supernova dust with a theoretical
model of dust formation in Type Ia remnants which predicts dust masses of
0.088(0.017) M\odot for ejecta expanding into surrounding densities of
1(5)cm-3. The model predicts that silicon- and carbon-rich dust grains will
encounter the interior edge of the observed dust emission at \sim400 years
confirming that the majority of the warm dust originates from swept up
circumstellar or interstellar grains (for Kepler and Tycho respectively). The
lack of cold dust grains in the ejecta suggests that Type Ia remnants do not
produce substantial quantities of iron-rich dust grains and has important
consequences for the 'missing' iron mass observed in ejecta.
View original:
http://arxiv.org/abs/1111.6627
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