EVIDENCE FOR WATER ICE AND ESTIMATE OF DUST PRODUCTION-RATE IN COMET HALE-BOPP AT 2.9 AU FROM THE SUN

We report observational evidence for water ice in comet C/1995 O1 (Hal e-Bopp) when it was at 2.9 AU from the Sun, from emission features at 44 and 65 mu m, and possibly an absorption feature at 3.1 mu m, observ ed with ISO/LWS and PHT. We find that icy grains have mean radii of 15 mu m within a factor of 2, lifetimes of similar to 2 days, a temperat ure of similar to 153 K, and a total mass of similar to 2 x 10(9) kg. From investigation of the continuum spectrum at 43-195 mu m, we also i nfer a production rate of large particles (similar to 100 mu m) dust o f about 4 x 10(4) kg s(-1).