title: Heterodyne spectroscopy of the J = 22-21 CO line in Orion.
abstract: We have observed the J = 22-21 line of 12CO at 2528 GHz (118.8 micrometers) in the IRc2 region of Orion.  The spectra at 0.6 km s-1 resolution show both plateau emission with FWHM approximately 35 km s-1 and a narrower component with FWHM approximately 8 km s-1.  Comparison with heterodyne data of similar quality on the J = 17-16 line indicates that the broad and narrow components both originate in gas with an excitation temperature Tex approximately 600 K.  The emission is consistent with the predictions of shock models in which the wide component arises from the heated outflow gas and postshock molecular material, while the narrow component comes from ambient material near the leading edge of the shock front where temperatures are high but significant acceleration has not yet occurred.
authors.affiliation: Space Sciences Laboratory, University of California, USA.
authors.forename: R T
authors.initials: RT
authors.lastname: Boreiko
authors.forename: A L
authors.initials: AL
authors.lastname: Betz
mesh_terms: D055580:Astronomical Phenomena; D001256:Astronomy; D002248:Carbon Monoxide / Q000032:analysis* / Q000737:chemistry*; D005118:Extraterrestrial Environment; D016011:Normal Distribution; D013055:Spectrophotometry, Infrared
chemical_list: D002248:Carbon Monoxide