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

The following document lists the file abstract/JLEQUEUX_CAMSFR.abs from catalogue VI/111.
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SCIENTIFIC ABSTRACT:
The aim of this proposal is to image with ISOCAM the infrared
emission of hot dust around 15 micrometers and some of the infrared emission
bands inside and in the surroundings of a variety of extragalactic HII regions.
The selected star-forming regions exhibit a range of strengths and chemical
compositions. They span an abundance range from 1/10 (SMC, NGC 5471 in M 101) 
to 3-4 times solar (CCM 71 and 72 in M 51). IZw 18 (1/30 solar) is in another
proposal. Observations with ISOCAM will be considerably more sensitive,
more complete and better calibrated than observations with other existing
means. The nature and the thermal properties of the hot dust which radiates
in the 10-20 micrometer wavelength range are not understood yet, although
it certainly contains silicates. This is also true for the carrier(s) of the
infrared bands, although there is some agreement that they may be PAHs or
related carbonaceous products. Both are likely to be strongly dependent on
the UV radiation field and on the chemical composition of the interstellar
matter. A comparison of the distribution of their infrared emission with
that of the ionized and neutral gas and of "normal" dust should contribute to
the understanding their physics and chemistry. Together with coordinated other
ISO and ground-based observations, it will also allow to study the structure
and the energy balance of these active regions.
OBSERVATION SUMMARY
Full LW CVF scans will be secured for the brightest HII region in each of the 
Magellanic Clouds, allowing also a study of atomic lines and extinction.
All the regions will be imaged with the following filters: LW2, LW3, LW4, LW6,
LW7, LW8 and LW10. The integration time will be 2 seconds and the pixel is 6".
The central region of 30 Dor will not be imaged with filters due to possible
saturation, and 8 fields will be imaged around using CAM01, together
with a distant reference field. The same will be done for N66 (small map). 
Otherwise Beam Switching (CAM03) will be used. This procedure is repeated for 
each filter and if possible observations with different filters are 
concatenated. In some cases observations of several targets in a given galaxy 
are concatenated as comparison is important. The expected S/N ratio is in
general larger than 10.