Some diatomic molecules from Halley's UV spectra near spacecraft flybys

Abstract

The abundances of diatomic molecules seen in the UV both give clues to the parent compounds and help unravel the gas and ion mass spectrometry. From IUE spectra of comet Halley, the authors find upper limits on SH and CS⁺ column densities, and estimates of probable NO, S₂, and SO. In particular, judged from the 226 nm γ-band, NO was relatively abundant at 2 - 8×10¹³cm^-2 on March 9 - 14. The production rate of S₂ was around 10²⁷ molecules s^-1 at that time, but both showed day-to-day variability by 2 - 3 times.