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Astron. Astrophys. 347, 258-265 (1999)

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86 and 140 GHz radiocontinuum maps of the Cassiopeia A SNR

H. Liszt 1 and R. Lucas 2

1 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475, USA
2 Institut de Radioastronomie Millimétrique, 300 Rue de la Piscine, F-38406 Saint Martin d'Hères, France

Received 2 February 1999 / Accepted 12 March 1999


MM-wave continuum emission from the Cassiopeia A SNR was mapped at 86 and 140 GHz using an on-the-fly beam-switching technique at NRAO's 12m telescope on Kitt Peak. Global nebular mm-wave fluxes follow quite well the [FORMULA] behaviour established previously at frequencies of 1-23 GHz and vary as [FORMULA] over the entire range 1-140 GHz. The 86 GHz excess found earlier by Kenney & Dent (1985) is not confirmed.

As suggested by Liszt & Lucas (1995) and as shown by the transition from off-source emission to on-source absorption in the HCO+ J=1-0 line, the mm-wave radiocontinuum is too feeble to permit reliable mm-wave absorption line spectroscopy using small singledish mm-wave radiotelescopes.

12CO J=2-1 and 13CO J=1-0 emission around the nebula was mapped more fully than was previously available. There is no striking evidence which would suggest an interaction between the SNR and ambient neutral gas.

Key words: ISM: abundances – ISM: molecules – ISM: supernova remnants – radio continuum: ISM

Send offprint requests to: H. Liszt (hliszt@nrao.edu)

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© European Southern Observatory (ESO) 1999

Online publication: June 18, 1999