The main objective of the proposal is the investigation of the Galactic interstellar medium (ISM) and, especially, of its constituents. This study is motivated by the fact that the ISM is the site in which matter in the Galaxy collapses into stars and is then rejected at the end of their life therefore providing a unique source of information for tracing the complete evolution from dust to stars and from these to the final supernova phase. The project , in particular, aims at the 3D reconstruction of the spatial distribution of the three thermal phases of the ISM gas (namely, molecular, neutral and ionised). This goal will be achieved by using an inversion method and such application will be innovative for the unprecedented consistent implementation of the ionised phase of the gas. This action will be performed in two steps: first by including HII regions (localized sources of ionised gas in the Galaxy) through the exploitation of velocity data which are available for a relevant number of these sources; then by implementing the diffuse ionised component thanks to the kinematics information encoded in recently obtained HII recombination lines data. The ionised gas component, which is currently the least known among the ISM gas phases, will be the subject of the second part of scientific analysis. Since one of the most puzzling questions concerns its detection in regions far from sites of star formation where ultraviolet radiation is expected to be, a new approach to this problem will be attempted, based on the observed correlation between dust and ionised gas. These two components of the ISM have been found to correlate on large angular scales but studies conducted on the scale of individual regions of stars formation seem to indicate that the correlation breaks down on these scale. Therefore a new window to scientific investigation may be opened by the use of dust as a tracer of the ionised gas.
Call for proposal
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