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N. Dello Russo (CUA@NASA-GSFC), M. J. Mumma (NASA-GSFC), K. Magee-Sauer (Rowan U.), E. L. Gibb (Univ. of Notre Dame), M. A. DiSanti (NASA-GSFC), B. P. Bonev (U. Toledo@NASA-GSFC)
Observations of comets with ground-based high-resolution infrared spectroscopy have retrieved a wealth of information on volatile abundances in bright long-period comets, but have achieved only limited success in characterizing the chemistry of fainter short-period comets. Recent advances in ground-based instrumentation, such as the high-resolution cross-dispersed NIRSPEC spectrometer at the Keck 2 Observatory, have permitted the in-depth study of fainter comets. We present volatile production rates and relative abundances for several molecules in comet 2P/Encke on three dates (UT November 4.3, 5.3, and 6.3, 2003) using NIRSPEC. Analysis of ro-vibrational lines of H2O and HCN suggest low gas rotational temperatures (~ 20-30 K) on these dates.
Observations of 2P/Encke with NIRSPEC yielded molecular lines with high signal-to-noise ratios. These data were used to assess the feasibility of detecting molecular species in two Jupiter-family comets available in the spring of 2005: 21P/Giacobini-Zinner (G-Z) and 9P/Tempel 1. G-Z is the prototypical C2 depleted comet, and prospects for detecting possible parents C2H2 and C2H6 (as well as other volatile species) will be explored. 9P/Tempel 1 is the target of the Deep Impact Mission. We will discuss prospects for determining pre-impact molecular abundances, and detecting changes in volatile abundances post-impact.
This work was supported by the NASA Planetary Atmospheres and Planetary Astronomy Programs, and the Keck PI Data Analysis Fund.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.