DUST IN A TYPE Ia SUPERNOVA PROGENITOR: SPITZER SPECTROSCOPY OF KEPLER'S SUPERNOVA REMNANT

Characterization of the relatively poorly understood progenitor systems of Type Ia supernovae is of great importance in astrophysics, particularly given the important cosmological role that these supernovae play. Kepler's supernova remnant, the result of a Type Ia supernova, shows evidence for...

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Bibliographic Details
Published in:The Astrophysical journal 2012-08, Vol.755 (1), p.1-8
Main Authors: WILLIAMS, Brian J, BORKOWSKI, Kazimierz J, REYNOLDS, Stephen P, OHAVAMIAN, Parviz, BLAIR, William P, LONG, Knox S, SANKRIT, Ravi
Format: Article
Language:English
Subjects:
ASTRONOMY
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
ASYMPTOTIC SOLUTIONS
CAMERAS
COSMIC DUST
COSMOCHEMISTRY
DENSITY
Dust
Earth, ocean, space
EMISSION
EMISSION SPECTROSCOPY
Exact sciences and technology
Infrared
INFRARED SPECTRA
IRON
OXYGEN
Progenitors (astrophysics)
SILICATES
STAR EVOLUTION
STELLAR ATMOSPHERES
SUPERNOVA REMNANTS
SUPERNOVAE
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Summary:Characterization of the relatively poorly understood progenitor systems of Type Ia supernovae is of great importance in astrophysics, particularly given the important cosmological role that these supernovae play. Kepler's supernova remnant, the result of a Type Ia supernova, shows evidence for an interaction with a dense circumstellar medium (CSM), suggesting a single-degenerate progenitor system. We present 7.5-38 mu m infrared (IR) spectra of the remnant, obtained with the Spitzer Space Telescope, dominated by emission from warm dust. Broad spectral features at 10 and 18 mu m, consistent with various silicate particles, are seen throughout. These silicates were likely formed in the stellar outflow from the progenitor system during the asymptotic giant branch stage of evolution, and imply an oxygen-rich chemistry. In addition to silicate dust, a second component, possibly carbonaceous dust, is necessary to account for the short-wavelength Infrared Spectrograph and Infrared Array Camera data. This could imply a mixed chemistry in the atmosphere of the progenitor system. However, non-spherical metallic iron inclusions within silicate grains provide an alternative solution. Models of collisionally heated dust emission from fast shocks (>1000 km s super(-1)) propagating into the CSM can reproduce the majority of the emission associated with non-radiative filaments, where dust temperatures are ~80-100 K, but fail to account for the highest temperatures detected, in excess of 150 K. We find that slower shocks (a few hundred km s super(-1)) into moderate density material (n sub(0) ~ 50-250 cm super(-3)) are the only viable source of heating for this hottest dust. We confirm the finding of an overall density gradient, with densities in the north being an order of magnitude greater than those in the south.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/755/1/3