Abstract Narrow band images of comet Giacobini-Zinner obtained near perihelion have near to 400 km resolution (1″ pixels). The [OI] images show isophotes close to circular and integral profiles over circular annuli show a central source region, presumed to describe release of H2O. Modelling the H2O and OH contributions and NH2 contamination leads to a scale for the source of 2000 km. The presumed H2O is being released from grains on this scale and proceeding in free molecular flight to populate the sunward and tailward comas uniformly. For analysis of CN and C2, integration over sunward and tailwards annular sectors distinguishes asymmetries due to radiative repulsion and Greenstein effects. The large-scale CN map has a smooth sunward profile characteristic of a wide range of emission speeds, 0.7–1.1 km/s, which favour a grain rather than molecular source. In the both large and small-scale images, some 20% residual sunward bias due to sun-side production is identified. Parent scales derived for CN and C2 of 1.2–2.0 and 1.8−2.4 × 104 km resp. could correspond to the scale for release from CHON grains, as hypothesised too for comet Halley. The wide range of low CN velocities inferred from coma profiles in comet G–Z, favours grain over molecular parameters for the bulk of the CN (and C2); though the speeds are lower than detected in comet Halley, this can reflect the lower gassing rate.


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    Title :

    Gas coma of comet Giacobini-Zinner: Emission from grains


    Contributors:

    Published in:

    Publication date :

    1989-01-01


    Size :

    4 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English




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