| Description |
Hi-GAL360 will use PACS and SPIRE in parallel mode to obtain a 5-band photometric survey of the Outer Galactic Plane (OGP, beyond the solar circle) in the longitude range complementary to the Hi-GAL Open Time KP, i.e., 68 < l < 288 in a 2-wide strip in latitude following the mid-plane of emission.Hi-GAL360 data will enable a complete census of temperature, mass, density, column density and luminosity of filaments, clumps, and cores in the less confused outer Galaxy, where the assembly of filamentary structures and clouds and their fragmentation into clumps and cores can be uniquely characterised in low-metallicity and HI-dominated environments that are so different with respect to the inner Galaxy. A complete OGP survey is required to obtain a statistically significant sampling of Galactic diversity - the full range of spiral arm, inter-arm, dust cloud, and star formation region properties - avoiding biases introduced by the study of specific or limited regions. Hi-GAL360, together with Hi-GAL, will chart the Star Formation Rate and Efficiency from the Galactic Center to the far outer Galaxy, mapping the location and properties of star formation thresholds, thus providing the much needed connection between global scaling laws and the diversity of physical processes at work in the Galaxy. It will lay the foundations for a predictive, quantitative model of how star formation is triggered and regulated on all scales in the Milky Way. Such a model is vital to a full understanding of galaxy formation and evolution.The merged Hi-GAL360/Hi-GAL Atlas of the Galaxy will provide essential ground truth for the interpretation of Herschel data on other galaxies from the Local Group to the high-redshift Universe where these objects are blended, and it will be the Herschel legacy that will remain unsurpassed for decades as the definitive survey of far-IR emission from the Galaxy. Given our demonstrated community-oriented approach, we again waive our proprietary period. |
