We present a comparative study of the inner comae of comets 1P/Halley and 19P/Borrelly using data from the Halley Multicolour Camera (HMC) onboard Giotto and the Miniature Integrated Camera and Spectrometer onboard Deep Space 1 (DS1). We show that the dust brightness dependence as a function of radial distance is different for both comets. We suggest that optical depth or fragmentation effects dominate the brightness distribution at comet 1P/Halley whereas acceleration or non-point source geometry effects dominate at comet 19P/Borrelly. The nightside profiles of comet 19P/Borrelly suggest a continuing non-radial outflow from the nucleus out to several tens of kilometres. This modifies the observed dayside to nightside brightness ratio with distance and offers a further constraint on dust emission models. By setting up a linear system of equations to fit the dust intensity distribution, better fits could be obtained by incorporating acceleration into the equation of free-radial outflow. Finally, we estimate the dust production rate of 19P/Borrelly at the time of DS1 encounter as no higher than 324 kg/s based on comparisons with HMC intensity measurements. ?? 2007 Elsevier Ltd. All rights reserved.
|Title||Comparison of the dust distributions in the innermost comae of comets-1P/Halley and 19P/Borrelly spacecraft observations|
|Authors||T.-M. Ho, N. Thomas, D. C. Boice, M. Combi, L. A. Soderblom, V. Tenishev|
|Publication Subtype||Journal Article|
|Series Title||Planetary and Space Science|
|Record Source||USGS Publications Warehouse|