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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[25.02] Spectroscopic Observations of Comets 42P/Neujmin 3 and 53P/Van Biesbroeck

J. Pittichova, B. Bus, K. J. Meech (IFA, Hawaii)

We present preliminary results from a spectroscopic study of short-period comets 42P/Neujmin 3 and 53P/Van Biesbroeck. These comets are of particular interest due their orbital histories. While their current orbits are very dissimilar, numerical integrations have shown that during January 1850 both comets approached within 0.1 AU of Jupiter. Prior to this encounter, their orbits were nearly identical, implying that these two comets share a common origin. If confirmed, the dynamical link between these two comets provides a unique opportunity to study the physical evolution of cometary fragments that have been separated for more than 150 years.

Our goal is to compare the dust and gas properties for these two comets as a means testing whether they are fragments of a disrupted parent. Spectra covering the visible-wavelength range from 0.32 to 0.80 microns were obtained using both the blue and red channels of the Low-Resolution Imaging Spectrometer (LRIS, Oke et al. 1995, PASP 107, 375) at Keck I on August 18, 2004. At the time of observation, 42P/Neujmin 3 was one month past perihelion, at a heliocentric distance r = 2.04 AU, while 53P/Van Biesbroeck was at a distance r = 3.41 AU, having passed through perihelion in October 2003. Both comets had an an apparent magnitude of V ~ 17. Data reduction has begun, with the blue channel observations for Neujmin 3 revealing spectral signatures for NH, CN, C2, and C3. This work will focus on determining fluxes for these gas species and constraining the dust-to-gas ratios for both comets.

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