36th DPS Meeting, 8-12 November 2004
Session 25 Comets Coma II
Oral, Thursday, November 11, 2004, 8:30-10:00am, Clark

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[25.03] HCN, C2H2, and NH3 abundances in comet C/LINEAR 2002 T7

K. Magee-Sauer (Rowan Univ.), N. Dello Russo (CUA at NASA's GSFC), M.A. DiSanti (NASA's GSFC), B. Bonev (Univ of Toledo at NASA's GSFC), E.L. Gibb (Notre Dame), M.J. Mumma (NASA's GSFC)

We present quantitative measurements of HCN, C2H2, and NH3 emissions near 3.0 \mum in comet C/LINEAR 2002 T7. The observations were obtained using the CSHELL instrument at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea. CSHELL incorporates a 256x256 InSb array detector with a long slit, which provides high spectral resolution (R ~ 2 x104) sufficient to resolve individual cometary emission lines, coupled with high spatial resolution for determining the distribution of species within the coma. The dates of observations were UT 2004 3May, 4 May, 6 May, 8 May and 9 May.

The high Doppler shift (~ - 65 km/s) of T7 during the early May time period made it an excellent target for detection of NH3. In other comets observed since Hyakutake, stronger lines of NH3 overlapped with atmospheric absorptions. Several lines of the Q-branch and R-branch of the \nu1 band were detected.

The apparition of T7 was also favorable for detection of the \nu3 band of C2H2 and resulted in detection of (at least) 6 ro-vibrational lines of the molecule, the greatest number of C2H2 lines detected in any comet to date.

We routinely observe a wide range of ro-vibrational lines of the \nu3 band of HCN in comets. In T7, at least 10 lines of the P- and R- branch were detected allowing an accurate determination of the rotational temperature and production rate.

Numerous other emissions were detected within these spectra (H2O hot-band emission, OH prompt emission, and NH2). Several (relatively strong) unidentified emission lines were also observed. Spectra, production rates, rotational temperatures, and relative abundances of HCN, C2H2, and NH3 will be presented and discussed.

KM-S would like to acknowledge support from the National Science Foundation RUI Program No. 0407052.

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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.