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B. P. Bonev (University of Toledo / NASA GSFC), M. J. Mumma, M. A. DiSanti (NASA GSFC), K. Magee-Sauer (Rowan University), N. Dello Russo (JHU/APL), D. P. Stark, R. S. Ellis (Caltech), E. L. Gibb (University of Notre Dame), J. Feuss (Rowan University)
Infrared prompt emission from OH has been observed at various frequencies in the L-band (2.9-3.7 ~\mum) and at heliocentric distances up to about 1.50~AU . These lines originate from vibrationally- and (highly) rotationally-excited states of OH generated by photolysis of H2O. These excited states cannot be produced efficiently by any other known mechanism, and this is the basis for considering the OH prompt emission as a proxy for water production in comets. In previous works, we presented quantitative analyses of the OH "quadruplet" near 3046 cm-1 in three comets (Bonev et al. 2004, Ap. J.; 2003, 2004 DPS talks). Here, we extend this work toward more than a dozen OH lines from the (1-0) band and several lines from the (2-1) band. We have completed our study of comet C/2000 WM1 (LINEAR) and are now working on a new very challenging, but high quality data set from comet C/2004 Q2 (Machholz). We will present prompt emission efficiencies [in photons sec-1 (H2O molecule) -1] for multiple OH lines that originate from quantum states spanning a wide range of rotational quantum numbers. Aside from quantifying water production, the measured prompt emission efficiencies provide information on the relative populations among the rotationally-excited states of OH produced by water photolysis. The parent-like spatial distribution of the OH prompt emission intensity provides a useful comparator for co-measured species like H2CO, that could have both native and extended components.
This work was supported by grants to M. J. Mumma (RTOP 344-32-30-07) under NASA's Planetary Astronomy Program.
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.