title: Collisional quenching of OH radio emission from comet Hale-Bopp.
abstract: Observations of comets in the 18-cm OH transitions offer a means to probe gas production, kinematics, and OH excitation in comets. We present initial results of OH observations of comet Hale-Bopp obtained with the NRAO 43 m antenna located in Greenbank, WV. Maps of the emission provide strong constraints on the amount of quenching of the inversion of the OH ground state A-doublet in the coma. Analysis of the total radio OH flux and maps of its radial brightness distribution indicate a quenched region on the order of approximately 500,000 km during March and April 1997. This large value is generally consistent with previous observations of radio OH quenching in lower production rate comets when the high production rate of comet Hale-Bopp is considered.
authors.affiliation: Five College Radio Astronomy Observatory, University of Massachusetts, Amherst 01003, USA. schloerb@fcrao1.phast.umass.edu
authors.forename: F P
authors.initials: FP
authors.lastname: Schloerb
authors.forename: C H
authors.initials: CH
authors.lastname: Devries
authors.forename: A J
authors.initials: AJ
authors.lastname: Lovell
authors.forename: W M
authors.initials: WM
authors.lastname: Irvine
authors.forename: M
authors.initials: M
authors.lastname: Senay
authors.forename: H A
authors.initials: HA
authors.lastname: Wootten
mesh_terms: D001256:Astronomy / Q000295:instrumentation; D005118:Extraterrestrial Environment; D005740:Gases / Q000032:analysis*; D017665:Hydroxyl Radical / Q000032:analysis*; D019110:Meteoroids; D013057:Spectrum Analysis
chemical_list: D005740:Gases; D017665:Hydroxyl Radical