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.
Instrument
CAM01 , CAM03 , CAM04
Temporal Coverage
1996-02-08T10:19:35Z/1997-10-04T10:27:47Z
Version
1.0
Mission Description
The Infrared Space Observatory (ISO) was the worlds first true orbiting infrared observatory. Equipped with four highly-sophisticated and versatile scientific instruments, it was launched by Ariane in November 1995 and provided astronomers world-wide with a facility of unprecedented sensitivity and capabilities for a detailed exploration of the Universe at infrared wavelengths.
European Space Agency, Lequeux et al., 1999, 'Spectro-imaging of individual star-forming regions in nearby galaxies.', 1.0, European Space Agency, https://doi.org/10.5270/esa-88034jq
