Excitation conditions and energetics of the dense gas in M17 SW

¹ European Southern Observatory, Santiago, Chile
² Max-Planck-Institut für Radioastronomie, Bonn, Germany
³ Kapteyn Astronomical Institute, Groningen, The Netherlands
⁴ I. Physikalisches Institut der Universität zu Köln, Köln, Germany

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Abstract

The chemical and energetic conditions created by radiative feedback are probed with observations of multiple molecular transitions toward M17 SW. Extensive maps, including the ¹²CO J = 16 → 15, J = 12 → 11, and J = 11 → 10 lines, as well as the HCN J = 8 → 7 and HCO⁺ J = 9 → 8 transitions, were obtained with the dual band receiver GREAT on board the SOFIA airborne telescope, and with the ground based APEX and IRAM 30 m telescopes. These data provide extensive line spectral energy distributions (LSEDs) of the CO, HCN and HCO⁺ molecules (and their isotopologues). The excitation conditions of the three species are estimated simultaneously using the same density and temperature in a two-phase non-LTE radiative transfer model of the LSEDs.