DPS Pasadena Meeting 2000, 23-27 October 2000
Session 44. Comets - Coma, Tails, Solar Wind Interaction II
Oral, Chairs: C. Lisse, D. Bockel\'ee-Morvan, Thursday, 2000/10/26, 10:30am-12:00noon, Little Theater (C107)

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[44.04] A survey of organic volatile species in comet C/1999 H1 (Lee) using NIRSPEC at the Keck Observatory

M. J. Mumma (NASA's GSFC), I. S. McLean (UCLA), M. A. DiSanti (CUA/NASA's GSFC), J. E. Larkin (UCLA), N. Dello Russo (CUA/NASA's GSFC), K. Magee-Sauer (Rowan Univ.), E. E. Becklin (UCLA), T. Bida, F. Chaffee, A. R. Conrad (CARA), D. F. Figer (STScI), A. M. Gilbert, J. R. Graham (UCB), N. A. Levenson (JHU), R. E. Novak (Iona Coll.), D. C. Reuter (NASA's GSFC), H. I. Teplitz (NOAO/NASA's GSFC), M. K. Wilcox (UCLA), Li-H. Xu (UNB)

The organic volatile composition of the long-period comet C/1999 H1 (Lee) was investigated using the first of a new generation of cross-dispersed cryogenic infrared spectrometers (NIRSPEC, at the Keck Observatory atop Mauna Kea, HI). On Aug. 19 - 21, 1999, the organics spectral region (2.9 -- 3.7 \mu m) was completely sampled at both moderate - and high - dispersion, along with the CO fundamental region (near 4.67 \mu m). Emission from water, carbon monoxide, methanol, methane, ethane, acetylene, and hydrogen cyanide was identified, and numerous new spectral lines were detected. Many new multiplets from OH in the 1-0 band were seen in prompt emission, providing an additional approach for detection of water in comets. Selected spectral extracts will be shown, and global production rates will be presented for seven parent volatiles. The detected hydrocarbons in Lee have abundances comparable to those found in other long-period comets, e.g. Hyakutake and Hale-Bopp. However, carbon monoxide is strongly depleted in comet Lee, demonstrating that chemical diversity occurred in the giant-planets' nebular region.

This work was supported by the NASA Planetary Astronomy Program under RTOP 344-32-30-07 to M. J. Mumma and Grant NAG5-7905 to M. A. DiSanti, by the NASA Planetary Atmospheres Program under Grant NAG5-7753 to N. Dello Russo, and by the National Science Foundation under Grant AST-9619461 to K. Magee-Sauer.

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