DPS 34th Meeting, October 2002
Session 16. Comets
Poster, Chair(s): , Tuesday, October 8, 2002, 3:30-6:00pm, Exhibit Hall

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[16.05] CSHELL Observations of Comet C/2002 C1 (Ikeya-Zhang) in the 3.0-Micron Region

K. Magee-Sauer (Rowan Univ.), N. Dello Russo, M. A. DiSanti (NASA GSFC/ CUA), E. Gibb (NAS-NRC, NASA GSFC), M. J. Mumma (NASA GSFC)

Comet C/2002 C1 (Ikeya-Zhang) was observed at the NASA Infrared Telescope Facility atop of Mauna Kea using the CSHELL instrument. CSHELL incorporates a 256x256 InSb array detector with a long slit, which provides high spectral resolution sufficient to resolve individual cometary emission lines. “Target of Opportunity” time was assigned to observe the comet. Daytime observations were acquired UT 2002 March 21, 22, 27 and April 10 – 13.

The comet’s production rate was high enough and the Doppler shift optimum for the first secure detection of several lines of NH3 in the infrared region. (NH3 was first securely detected in comets in the radio region [1,2, 3]). A search for C4H2 was also attempted with a tentative detection/upper limit. Detection of C4H2 is restricted to infrared wavelengths since it is a symmetric hydrocarbon (no permanent dipole moment exists). This tentative detection is the first estimate of the relative abundance of C4H2 in comets.

Numerous HCN ro-vibrational lines were detected enabling the determination of HCN production rates and rotational temperatures. C2H2 was also detected and production rates are obtained. Other molecules detected in this region are H2O (hotband emission), OH (prompt emission), NH2, and numerous unidentified lines.

KM-S would like to acknowledge the support the National Science Foundation (grant no. 0098411) under the Research at Undergraduate Institutions Program. We would also like to acknowledge telescope operators, D. Griep and L. Bergknut, who enabled these daytime observations with their expertise and willingness to accommodate the extra time assigned to their schedules. Special thanks to A. Tokunaga and the IRTF for providing the opportunity for daytime observations.

[1] M. Byrd et al. (1997) Astron & Astrophys, 325. [2] A. Wooten et al. (1996) ACM. [3] B. Butler et al. (2002) ACM.

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Bulletin of the American Astronomical Society, 34, #3< br> © 2002. The American Astronomical Soceity.