A rotational-state population analysis of the high-resolution IUE observation of CS emission in comet P/Halley

Abstract

The high resolution spectrum of comet P/Halley has been measured in the region of the CS emission. CS in comet Halley is produced by photodissociation of CS₂ and subsequently re-excited by broad band solar radiation. An inversion procedure is introduced to extract the rotational population distribution from the dispersed fluorescence spectrum. The fluorescence profile from the R branch of the υ' = 0 to υ'' = 0 is analyzed using this method. The extracted rotational distribution shows a peak at J'' = 1 superimposed on a background extending to J'' = 29. The distribution is interpreted by considering radiative and collisional relaxation processes in the comet. Intensity anomalies in the wavelength region corresponding to P and Q branch emission are considered.