Published online by Cambridge University Press: 19 September 2017
We used the BIMA Array to observe CO and CS molecules in Comet Hale-Bopp (C/1995 O1) during the 1997 apparition. A spur-like structure around the cometary nucleus is observed. These molecular spurs may be attributed to gas or dust jets. Using Haser model, we find the theoretically predicted CO scale length agrees well with observations. A large fraction of CO is sublimated directly from the nucleus, with the remaining CO coming from icy dust grains in cometary coma. The [CO/H2O] abundance ratio of Hale-Bopp is consistent with that of icy dust grains in star forming regions. We conclude that Hale-Bopp was likely formed at the stage when there were still ample of icy grains in Solar Nebula; therefore, abundances of parent molecules in a comet may reflect the primordial chemical composition of the Nebula.