Sagittarius B1: A Patchwork of H ii Regions and Photodissociation Regions

Abstract Sgr B1 is a luminous H ii region in the Galactic center immediately next to massive star-forming giant molecular cloud B2 and apparently connected it from their similar radial velocities. In 2018 we showed SOFIA FIFI-LS observations of [O iii ] 52 88 ? m lines that there no central exciting star cluster ionizing stars must be widely spread throughout region. Here present i 146 [C 158 formed surrounding photodissociation regions (PDRs). We find these correlate neither with each other nor although together they better 70 Herschel PACS images Hi-GAL. infer this consists number smaller plus associated PDRs, some seen face-on others more or less edge-on. used PDR Toolbox estimate densities far-ultraviolet intensities PDRs. Using models computed Cloudy, demonstrate possible appearances edge-on PDRs show density difference between electron estimated line ratios incompatible pressure equilibrium unless substantial contribution either turbulence magnetic field both. also conclude hot are spaced at distances gas evidence current formation.