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A&A Supplement series, Vol. 127, February I 1998, 479-495

Received September 6, 1996; accepted April 30, 1997

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

R. Umbachtex2html_wrap1955,gif - K. Jockerstex2html_wrap1955 - E.H. Geyertex2html_wrap1959

Send offprint request: K. Jockers

tex2html_wrap1961  Max-Planck-Institut für Aeronomie, Postfach 20, 37189 Katlenburg-Lindau, Germany
tex2html_wrap1963  Sternwarte der Universität Bonn, Observatorium Hoher List, 54550 Daun, Germany


Multislit spectra of comet P/Halley were obtained on April 10, 1986, using a focal reducer with a field of tex2html_wrap_inline1937 angular diameter. The number and arrangement of the slits allowed a reconstruction of the spatial distribution of principal neutral and ionic coma constituents within a frame of about tex2html_wrap_inline1939 at the comet. Radial profiles and two-dimensional maps for the dust continuum, CN, tex2html_wrap_inline1941, CH, tex2html_wrap_inline1943, and especially tex2html_wrap_inline1945, are presented in absolute intensity and column density 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 direction and form a plateau extending from the nucleus into the antisolar direction. The distribution of tex2html_wrap_inline1945 shows a stronger decrease in the tailward direction than that of tex2html_wrap_inline1943.

keywords: comets: individual: P/Halley -- multislit spectra -- molecular ions -- radicals -- spatial distribution

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