| Description |
Hi-GAL2pi will complete the 5-band far-IR survey of the Galactic Plane (GP), using PACS and SPIRE in pMode to map the two Galactic longitude areas that are not covered by the Hi-GAL KP nor its OT1 extension to the outer Galaxy. These two virgul60 longitude-wide slices centered toward the cardinal directions l=90 and l=270 include critical regions with uniquely favourable observing conditions found nowhere else in the Galaxy: a) the longest available panoramic view of the Persus Arm, which is the arm with the least foreground contamination from the sun.s viewpoint; b) the largely unexplored inter-arm region between the Persus and Carina Arms that spans most of the l=270 slice, that alone can be observed relatively free of confusion from our vantage point.The complete census of temperature, mass, and luminosity of filaments, clumps, cores and YSOs in these two regions will provide a spatially resolved measurement of the arm/inter-arm contrast in star formation rate (SFR) and efficiency (SFE), as well as a panoramic and unconfused view of the SFR and SFE along a full spiral arm extending from the Molecular Ring to the outer co-rotation Galactocentric radius. These observables, not accessible in the GP area covered in Hi-GAL KP or OT1 programs, will uniquely enable the critical steps in our understanding of the mechanisms responsible for the assembly, formation and fragmentation of the HI superclouds and the molecular clouds on spiral arms, and thus lay the foundations for a predictive global model of star formation in the Galaxy, that may serve as a template for Extragalactic studies. The completion of the Herschel Galactic Plane survey will establish a unique legacy that will be a keystone for all future Galactic and much extragalactic research, with data products that will be mined for decades by future generations and used for research not yet envisioned, with rich potential for serendipitous discoveries. Given our demonstrated community-oriented approach, we again waive our proprietary period. |
