Mid-J CO shock tracing observations of infrared dark clouds II Low-J CO constraints on excitation, depletion, and kinematics

Abstract

Infrared dark clouds are kinematically complex molecular structures in the interstellar medium that can host sites of massive star formation. We present 4 square arcminute maps of the 12CO, 13CO, and C18O J = 3 to 2 lines from selected locations within the C and F (G028.37+00.07 and G034.43+00.24) infrared dark clouds (IRDCs), as well as single pointing observations of the 13CO and C18O J = 2 to 1 lines towards three cores within these clouds. We derive CO gas temperatures throughout the maps and find that CO is significantly frozen out within these IRDCs. We find that the CO depletion tends to be the highest near column density peaks, with maximum depletion factors between 5 and 9 in IRDC F and between 16 and 31 in IRDC C. We also detect multiple velocity components and complex kinematic structure in both IRDCs. Therefore, the kinematics of IRDCs seem to point to dynamically evolving structures yielding dense cores with considerable depletion factors.

23 pages, 20 figures, accepted by A&A

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Cited by in corpus (11)

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• Probabilistic detection of spectral line components
• The chemical structure of young high-mass star-forming clumps: (I) Deuteration
• A multi-wavelength observation and investigation of six infrared dark clouds
• Similar complex kinematics within two massive, filamentary infrared dark clouds
• A simple approach to CO cooling in molecular clouds
• Mid-J CO Shock Tracing Observations of Infrared Dark Clouds III: SLED fitting
• Carina's Pillars of Destruction: the view from ALMA