Contents of: VI/111/./abstract/DPEQUIGN_ISM_III.abs

The following document lists the file abstract/DPEQUIGN_ISM_III.abs from catalogue VI/111.
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SCIENTIFIC ABSTRACT
Large amounts of cold nuclearly processed gas (primarily oxygen and iron)
are expected to be present in the inner unshocked regions of young supernova
remnants (SNRs). It is proposed to detect and establish characteristics of this
material by means of fine-structure lines. About 20 targets are considered, some
of which being observed at several positions.

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. Current information from X-ray, UV, and optical
studies is scarce and far-IR spectroscopy appears as a valuable alternative. 
Information about the dominant elements present in the inner part of SNRs 
(e.g., O, Ne, Si, S, Fe, and Ni) will provide a basis to connect SNRs to the 
events from which they were born. SN1987a is clearly a special target.

OBSERVATION SUMMARY
The grating mode of ISO/LWS is well-suited to this programme since overall
velocity fields of a few thousand km/s are typical. Wavelength oversampling
should provide useful information on velocities in bright objects. Full
grating spectra are necessary in most cases because SNRs are complex objects.
The probability of "unexpected" spectral features and of projection of
different components of the SNR in the observation lobe is large.

The targets should include all classical young SNRs because they are all 
different and even their progenitors may be controversial. In a few cases 
several positions should be observed to study composition variations and to 
allow subtraction of possible "foreground" emission from, e.g., the outermost 
shocked ISM. This "foreground" emission is evidently most interesting in 
studying other aspects of SNRs (interstellar shocks, dust heating, 
molecules...) not explicitly considered here. This "multipurpose" aspect of any 
spectroscopic programme about young SNRs should be kept in mind.

Since the proposal mainly concerns detection of emission lines of ionic
species not expected in the background emission, no "off-source" positions are
considered.


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