Examination of Fragment Species in the Comae of Several Comets Using an Integral Field Unit Spectrograph

Abstract

Abstract Spectra of the comae of four comets were obtained with an integral field unit spectrograph on the Harlan J. Smith Telescope at McDonald Observatory. The passband of the spectrograph permitted the observation of C2, C3, CH, CN, and NH2 transitions for these comets. The classical Haser model was used to derive production rates for each observed species. The production rates obtained for the comets were also used to obtain mixing ratios relative to CN. The relative abundances with respect to CN obtained for these comets vary greatly, but are largely consistent with ranges established from prior comet chemistry surveys. The notable exception is 168P/Hergenrother, which the results suggest is extremely depleted in volatiles, even with respect to many other comets designated as volatile depleted in prior surveys. The results for comet Hergenrother add to a small, but growing, body of data suggesting that there may be a subgroup of carbon-chain-depleted Jupiter-family comets that are also depleted in ammonia.