Chemistry in cometary comae.
Significant gas-phase chemistry occurs in the comae of bright comets, as is demonstrated here for the case of Comet Hale-Bopp. The abundance ratio of the two isomers, hydrogen cyanide and hydrogen isocyanide, is shown to vary with heliocentric distance in a way that is consistent with production of HNC by ion-molecule chemistry initiated by the photoionization of water. Likewise, the first maps of emission from HCO+ show an abundance and an extended distribution that are consistent with the same chemical model.
Irvine
W M
WM
Five College Radio Astronomy Observatory, University of Massachusetts, Amherst 01003, USA.
Dickens
J E
JE
Lovell
A J
AJ
Schloerb
F P
FP
Senay
M
M
Bergin
E A
EA
Jewitt
D
D
Matthews
H E
HE
D055580:Astronomical Phenomena; D001256:Astronomy; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003485:Cyanates / Q000032:analysis* / Q000737:chemistry; D005740:Gases; D006856:Hydrogen Cyanide / Q000032:analysis* / Q000737:chemistry; D019110:Meteoroids
D003485:Cyanates; D005740:Gases; D006856:Hydrogen Cyanide; C005057:isocyanic acid