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Astron. Astrophys. 352, L111-L115 (1999)

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Letter to the Editor

Element mixing in the Cassiopeia A supernova *

T. Douvion 1, P.O. Lagage 1 and C.J. Cesarsky 1,2

1 CEA/DSM/DAPNIA/Service d'Astrophysique, CE Saclay, 91191 Gif-sur-Yvette, France
2 European Southern Observatory, Karl-Schwarzchild-Strasse 2, 85748 Garching bei München, Germany

Received 7 September 1999 / Accepted 14 October 1999


Thanks to mid-infrared observations, we provide new clues to the element mixing during a supernova explosion by probing the mixing between three adjacent layers: the oxygen burning products layer (sulfur, argon,...), the silicate layer and the neon layer. The silicate and neon layers are both contaminated by sulfur and argon in a macroscopic way, but appear segregated, so that the mixing is heterogeneous. This finding complements the microscopic mixing information deduced from presolar grains found in meteorites and implies that, at present time, supernovae are probably not the main dust factory in the Galaxy. The mixing is often interpreted in terms of hydrodynamical instabilities driven by the outward shock following the implosion of the supernova core. Testing whether such instabilities can lead to the injection of material from a layer into upper layers without complete mixing, as suggested by the observations presented in this paper, should be possible with the intense lasers which are starting to be used to simulate astrophysical plasmas.

Key words: ISM: supernova remnants – infrared: ISM: continuum – infrared: ISM: lines and bands

* Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands and the United Kingdom) and with the participation of ISAS and NASA, and on observations obtained at the Canada-France-Hawaii Telescope.

Send offprint requests to: T. Douvion (tdouvion@cea.fr or lagage@cea.fr)

© European Southern Observatory (ESO) 1999

Online publication: December 2, 1999