Volume 587, March 2016
|Number of page(s)||23|
|Section||Interstellar and circumstellar matter|
|Published online||24 February 2016|
Mid-J CO shock tracing observations of infrared dark clouds
1 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
2 Department of Physics and Astronomy, The University of Western Ontario, London, N6A 3K7, Canada
3 Joint Astronomy Centre, 660 North A’ohoku Place, University Park, Hilo, HI 96720, USA
4 NRC-Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
5 Department of Physics and Astronomy, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
6 INAF−Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
7 Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, PO Box 3-72, 58090 Morelia, Michoacán, Mexico
8 Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
9 Department of Physics and Astronomy, San Jose State University, One Washington Square, San Jose, CA 95192-0106, USA
10 Space Science and Astrobiology Division, MS 245-3, NASA Ames Research Center, Moffett Field, CA 94035, USA
11 Department of Physics and Astronomy, University College London, 132 Hampstead Road, London NW1 2PS, UK
12 Departments of Astronomy & Physics, University of Florida, Gainesville, FL 32611, USA
Received: 10 August 2015
Accepted: 16 December 2015
Infrared dark clouds are kinematically complex molecular structures in the interstellar medium that can host sites of massive star formation. We present maps measuring 4 square arcminutes 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.
Key words: ISM: clouds / stars: formation / ISM: molecules / ISM: kinematics and dynamics / ISM: structure / ISM: abundances
Based on observations carried out with the JCMT and IRAM 30 m Telescopes. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).
IRAM CO observations are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (220.127.116.11) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/587/A96
© ESO, 2016
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