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ISO LWS and SWS spectroscopy of young supernova remnants

S. J. Unger ¹, D. Péquignot ², J. P. Baluteau ³, P. Cox ⁴, R. J. Emery ⁵, M. R. Haas ⁶, F. Lahuis ⁷, S. J. Leeks ¹, & C. Morisset ²

¹ Queen Mary and Westfield College, London, UK

² DAEC, Observatoire de Paris-Meudon, France ³ LAS Marseille, France ⁴ Institut d'Astrophysicque Spatiale, Orsay, France ⁵ Space Science Dept., RAL, Oxford, UK ⁶ NASA Ames, Moffett Field, USA ⁷ Space Research Organization Netherlands, Gronigen, NL

Determining the mass and chemical composition of supernova ejecta is crucial for three theories: stellar evolution, supernova explosions, and galactic evolution. This is a priori best performed in young SNRs in which mixing with the ISM is not yet achieved. Guaranteed-time Long Wavelength Spectrometer (LWS) and Short Wavelength Spectrometer (SWS) observations have shown atomic fine-structure line emission in a number of young supernova remnants (SNR) in the Galaxy and the Magellanic Clouds. Continuum dust emission was also detected.

The LWS observations were in the low resolution grating mode ( $R=\lambda/\delta\lambda \sim 200$ ) with full wavelength coverage from 43 to 197 $\mu$ m. The SWS observations were also in the low resolution grating mode ( $R=\lambda/\delta\lambda \sim$ 1000 to 4000) with full wavelength coverage from 2 to 45 $\mu$ m).

In this poster we focus on two prototypes. Cas A is the youngest ( $\sim$ 315 years) known SNR in our Galaxy and it is the prototype oxygen rich shell-type SNR. We map the main O-rich shell associated with the reverse shock, the centre and the optical jet. Broad [O III ] 52 and 88 $\mu$ m and [O I ] 63 $\mu$ m emission lines with strongly blue- and red-shifted material, extending over $\sim$ 10000kms^-1, are detected. The SWS observations reveal $\sim$ 3000kms^-1, blueshifted [O IV ] 26 $\mu$ m, [Ar II] $7\mu$ m, [Ar III] $9\mu$ m, [S IV] $10.5\mu$ m, [S III] 19 $\mu$ m, [Ne II] 12.8 $\mu$ m and [Ne III] 15.5 $\mu$ m emission lines with a much fainter redshifted component.

The Crab is thought to be the `prototype' of a class of remnants known as `Plerions'. These sources have a synchrotron nebula, assumed to be powered by a central pulsar, with no evidence for any shell emission from the supernova explosion. We mapped the Crab nebula at four positions. In projection near to the centre of the nebula we detect [Ne II] 12.8 $\mu$ m, [Ne III] 15.5 $\mu$ m, [O IV ] 26 $\mu$ m, [S III] 19 $\mu$ m,[S III] 33 $\mu$ m, [O III ] 52 $\mu$ m, [N III ] 57 $\mu$ m [O I ] 63 $\mu$ m, [O III ] 88 $\mu$ m, [N II ] 122 $\mu$ m, [O I ] 145 $\mu$ m, and [C II ] 158 $\mu$ m emission.

Next: Dust-gas separation in the Up: Poster session D Stars Previous: Gas and dust around

"The Universe as seen by ISO", 20 - 23 October 1998, Paris: Abstract Book