AAS 203rd Meeting, January 2004
Session 111 Interstellar Medium II
Poster, Thursday, January 8, 2004, 9:20am-4:00pm, Grand Hall

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[111.12] A Map of OMC-1 in CO J=9-8 (1.037 THz)

D. P. Marrone, J. Battat, F. Bensch, R. Blundell, T. Hunter, D. Loudkov, S. Paine, C.-Y. E. Tong (CfA), D. Meledin (Chalmers University of Technology), H. Gibson (RPG Radiometer Physics GmbH), S. Radford (NRAO), M. Diaz (Boston University)

The distribution of 12C16O J=9-8 (1.037 THz) emission has been mapped in OMC-1 at 35 points with 84'' resolution. This is the first map of this source in this transition and only the second velocity-resolved ground-based observation of a line in the terahertz frequency band. There is emission present at all points in the map, a region roughly 4' by 6' in size, with peak antenna temperature dropping only near the edges. Away from the Orion KL outflow, most of the emission comes from the OMC-1 photon-dominated region with a typical linewidth of 4-6 km s-1. Large velocity gradient modeling of the emission in J=9-8 and six lower transitions suggests that the lines originate in regions with temperatures around 120 K and densities around 104 cm-3 near \Theta1C Ori and at the Orion Bar, and from 70-80 K gas at slightly lower density southeast and west of the bar.

These observations were made with the 0.8 m Smithsonian Astrophysical Observatory Receiver Lab Telescope, located at an extremely high (5525 m) and dry site in Northern Chile. At this site atmospheric windows above 1 THz allow observations of several rotational transitions of CO, along with the ground state transition of N+ and many other common and exotic atomic and molecular lines previously unobserved from the ground.

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.