THE SPECTRUM AND SPATIAL-DISTRIBUTION OF CYANOGEN IN COMET HALE-BOPP (C 1995-O1) AT LARGE HELIOCENTRIC DISTANCE/

Optical spectra of comet Hale-Bopp (C/1995 O1) at a heliocentric dista nce of 6.45 astronomical units showed emission from cyanogen gas. The spatial distribution of cyanogen was considerably more diffuse and ext ended compared to the spatial profile of the dust or grains which were sharply peaked near the center. This behavior is consistent with come ts at smaller heliocentric distances suggesting the same or a similar formation mechanism, A cyanogen gas production rate of (1.2 +/- 0.3) x 10(26) molecules per second was derived. A model band profile derived from fluorescence equilibrium calculations for the comet's heliocentr ic velocity and distance agrees with the observed band profile.