IfA-98-7

A Determination of the HDO/H₂O Ratio in Comet C/1995 O1 (Hale-Bopp)

Roland Meier and Tobias C. Owen
University of Hawaii, Institute for Astronomy
meier@ifa.hawaii.edu

Henry E. Matthews
National Research Council of Canada, Herzberg Institute of Astrophysics
and Joint Astronomy Centre, Hilo, Hawaii

David C. Jewitt
University of Hawaii, Institute for Astronomy

Dominique Bockelée-Morvan
Observatoire de Paris-Meudon

Nicolas Biver
University of Hawaii, Institute for Astronomy

Jacques Crovisier and Daniel Gautier
Observatoire de Paris-Meudon

Science 279, 842-844 (6 February 1998)

Deuterated water (HDO) was detected in comet C/1995 O1 (Hale-Bopp) with the use of the James Clerk Maxwell Telescope on Mauna Kea, Hawaii. The inferred D/H ratio in Hale-Bopp's water is (3.3 ± 0.8) x 10^-4. This result is consistent with in situ measurements of comet P/Halley and the value found in C/1996 B2 (Hyakutake). This D/H ratio, higher than that in terrestrial water and more than 10 times the value for protosolar H₂, implies that comets cannot be the only source for the oceans on Earth.