Spatial distribution of neutral and ionic constituents in comet P/Halley

Abstract

Multislit spectra of comet P/Halley were ob- tained on April 10, 1986, using a focal reducer with a eld of 0:5 angular diameter. The number and ar- rangement of the slits allowed a reconstruction of the spa- tial distribution of principal neutral and ionic coma con- stituents within a frame of about 4 10 5 41 0 5 km 2 at the comet. Radial proles and two-dimensional maps for the dust continuum, CN, C3 ,C H, CO + , and especially CO + , are presented in absolute intensity and column den- sity units, respectively. Scale lengths and production rates for the radicals were determined within the Haser model. The molecular ions are not only restricted to the plasma tail but are also present in the sunward coma. Instead of forming a peak at the nucleus like the neutral radicals the ion column densities decrease rapidly in the solar direc- tion and form a plateau extending from the nucleus into the antisolar direction. The distribution of CO + shows a stronger decrease in the tailward direction than that of CO + .