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SCIENTIFIC ABSTRACT It is our aim to use innovative techniques, made possible by the use of ISO instrumentation, to investigate the parameters that control the formation of stars in stellar systems. To this end, estimates of the stellar mass, in several regions of recent star formation, as well as a variety of measurements revealing the physical properties (density, metal content, gas to dust ratio, temperature, mass, etc) of the star forming clouds are envisaged. The project demands a well coordinated investigation of regions of recent star formation in a variety of galaxies, in order to determine the various factors that control the strength of a star formation burst. Thus, the aim is to infer the total mass in newly formed stars as well as the properties of the star forming cloud, to determine in this way a definite correlation. With this aim in mind, we propose to investigate in detail the far IR properties of star forming regions. OBSERVATION SUMMARY Each object on the list will be mapped with ISOPHOT-C at wavelengths sensitive to the presence of dust, like 64, 93 and 152 microns. This will provide information about the mass of dust, extinction and the distribution of ionizing sources. We propose to use filters at 60, 90, 135 and 160 microns. For all sources the expected S/N in the PHT-C maps should be higher than 10 with 32 second integration time, which is then selected as a default for the maps except where otherwise is stated. The observations will use stare mode as as the extent of the objects can be larger than 180". The HII regions in M33 and M101 galaxies, which form the target list for the LWS observations, have been explicity excluded from the PHT-C list since they will be mapped in a different proposal by Hippelein et al. For 30Dor we propose to map the central 12x12 arcminutes in the same filters, plus one frame per filter out of the region for background estimation, due to its huge extension in the FIR, and use only 16 seconds of integration time per frame, which will be enough to provide a reasonable S/N ratio. Optical spectra at the peaks of the emission maps will be taken in order to determine and model the relative contribution of young stars in heating the dust. This will allow an estimate as accurate as posible of the number of ionizing sources. For bright objects, like the giants HII regions in M33 and M101 listed below, IR emission lines from the ionized gas will be observed at selected areas within the star forming regions, using LWS with three grating positions to map the OIII line at 52 and 88 microns and NIII lines at 57 microns. The strength of the lines in all cases is expected to be high enough to permit minimum integration time. Target list for LWS =================== Source RA DEC m33_ngc588 01 29 56.600 +30 23 30.000 m33_ngc59 01 30 22.600 +30 23 20.000 m33_ngc595 01 30 44.000 +30 26 25.000 m33_ngc604 01 31 43.300 +30 31 54.000 m33_ic131 01 30 23.200 +30 30 02.000 m33_ic132 01 30 26.900 +30 41 19.000 m33_ic142 01 31 05.900 +30 30 02.000 m101_ngc5447 14 00 42.900 +54 30 42.000 m101_ngc545 14 01 15.700 +54 28 59.000 m101_ngc5461 14 01 55.100 +54 33 30.000 m101_ngc5462 14 02 07.000 +54 36 20.000 m101_ngc5471 14 02 43.200 +54 37 57.000