DEUTERIUM IN COMET C-1995-O1 (HALE-BOPP) - DETECTION OF DCN

Deuterated hydrogen cyanide (DCN) was detected in a comet, C/1995 O1 ( Hale-Bopp), with the use of the James Clerk Maxwell Telescope on Mauna Kea, Hawaii. The inferred deuterium/hydrogen (D/H) ratio in hydrogen cyanide (HCN) is (D/H)(HCN) = (2.3 +/- 0.4) x 10(-3). This ratio is hi gher than the D/H ratio found in cometary water and supports the inter stellar origin of cometary ices. The observed values of D/H in water a nd HCN imply a kinetic temperature greater than or equal to 30 +/- 10 K in the fragment of interstellar cloud that formed the solar system.