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Published July 20, 2009 | Published
Journal Article Open

Spitzer Observations of the Young Core-Collapse Supernova Remnant 1E0102-72.3: Infrared Ejecta Emission and Dust Formation

Abstract

We present Spitzer Infrared Spectrograph and Infrared Array Camera observations of the young supernova remnant E0102 (SNR 1E0102-7219) in the Small Magellanic Cloud. The infrared spectra show strong lines of Ne and O, with the [Ne II] line at 12.8 μm having a large velocity dispersion of 2000-4500 km s^(–1) indicative of fast-moving ejecta. Unlike the young Galactic SNR Cas A, E0102 lacks emission from Ar and Fe. Diagnostics of the observed [Ne III] line pairs imply that [Ne III] emitting ejecta have a low temperature of 650 K, while [Ne V] line pairs imply that the infrared [Ne V] emitting ejecta have a high density of ~10^4 cm^(–3). We have calculated radiative shock models for various velocity ranges including the effects of photoionization. The shock model indicates that the [Ne V] lines come mainly from the cooling zone, which is hot and dense, whereas [Ne II] and [Ne III] come mainly from the photoionization zone, which has a low temperature of 400-1000 K. We estimate an infrared-emitting Ne ejecta mass of 0.04 M_⊙ from the infrared observations, and discuss implications for the progenitor mass. The spectra also have a dust continuum feature peaking at 18 μm that coincides spatially with the ejecta, providing evidence that dust formed in the expanding ejecta. The 18 μm peak dust feature is fitted by a mixture of MgSiO_3 and Si dust grains, while the rest of the continuum requires either carbon or Al2O3 grains. We measure the total dust mass formed within the ejecta of E0102 to be ~0.014 M_⊙. The dust mass in E0102 is thus a factor of a few smaller than that in Cas A. The composition of the dust is also different, showing relatively less silicate and likely no Fe-bearing dust, as is suggested by the absence of Fe-emitting ejecta.

Additional Information

© 2009 The American Astronomical Society. Received 2009 February 28; accepted 2009 April 27; published 2009 July 6. We thank Haley Gomez for insightful, helpful comments on the manuscript. J.R. thanks Pierre-Olivier Lagage, Sacha Hony, and Anne Decourchelle for fruitful discussion on dust and SN ejecta during her visit to Saclay. We thank Lee Armus and David Shupe for sharing the results of the IRS wavelength calibration on the IRS instrumental line widths, and Steven Finkelstein and William Blair for sharing their digitalized formats of HST and the optical images, and Shaun Amy for a radio image. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. Partial support for this work was provided by NASA through an GO award issued by JPL/Caltech.

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August 21, 2023
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