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Infrared spectroscopy of young supernova remnants heavily interacting with the interstellar medium *
I. Ionized species in RCW 103
E. Oliva 1,
A.F.M Moorwood 2,
S. Drapatz 3,
D. Lutz 3 and
E. Sturm 3
Received 16 October 1998 / Accepted 22 December 1998
ISO spectral observations of the supernova remnant RCW103 are presented. This object is the prototype of relatively young remnants ( yr) with fast shocks ( km s-1) interacting with dense interstellar medium.
The spectrum is dominated by prominent lines of [NeII], [SiII], [FeII] and other low excitation species which provide, for the first time, a simple and reliable estimate of the gas abundances of refractory (Si, Fe, Ni) and non-refractory (Ne, P, S, Cl, Ar) species. Apart from nickel, all the derived abundances are close to solar, confirming that the shock has destroyed all dust grains. Like the optical nickel lines, [NiII]6.64 µm yields Ni abundances a factor 10 solar which we propose results from a large underestimation of the computed Ni+ collision strengths.
The observed intensities and velocity widths of ionic lines are compatible with emission from the post-shock region alone with only a very small (if any) contribution from the photoionized precursor. This result does not agree with shock models which predict that the precursor should emit powerful line emission, especially from highly ionized species. The possible consequence of this on the modelling of Seyfert spectra is briefly discussed.
Key words: atomic data ISM: abundances ISM: individual objects: RCW 103 ISM: supernova remnants galaxies: spiral 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.
Send offprint requests to: E. Oliva
Online publication: March 1, 1999