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

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SCIENTIFIC ABSTRACT:
We propose a coherent program to study HII regions in
selected normal (non-interacting, non-starburst, non-AGN) galaxies in the
near- to far-IR in coordination with the ISOPHOT, the LWS and the SOT
consortia. The present part of the proposal consists in imaging all the
targets in two filters: LW 2 (5.0-8.5 micrometers) and LW 3 (12-18
micrometers). Emission in LW 2 will be dominated by IR emission bands and
emission in LW 3 by hot dust. The nature and physics of both components
are not well understood, and the IRAS 12 micrometer filter did not allow
a clear separation between them. However IRAS and other observations have shown
that the intensity of the IR bands and to some extent of hot dust (with
respect to colder dust) are affected by the UV radiation field and by
metallicity, and also that the IR band carrier(s) (PAHs or related large
molecules) are easily frozen on bigger grains or liberated from them. The
planned observations will allow a much better understanding of these
phenomena. Together with the other coordinated ISO observations and
complementary ground-based observations they will yield a more complete picture
of the physics of dust and possibly a full understanding of the thermal
balance of dust and gas in galaxies. The chosen targets span a large range
of properties and of distances, starting from the Magellanic Clouds where
very detailed studies will be possible and including more distant galaxies.
OBSERVATION SUMMARY
The observations combine the beam switching mode between the central region and
a reference point, far away from the galaxy, and a raster map with some
overlap between successive images. Filters LW2 and LW3 are used in every
case. The integration time is 2 sec. The expected sensitivity is a S/N ratio =
3 at the limit of the IRAS maps of extended galaxies.