Comet-Solar Wind Interaction: Dynamical Length Scales and Models

While the ICE magnetometer measurements at Comet Giacobini-Zinner led to a number of unexpected discoveries such as the intense hydromagnetic turbulence, the large-scale structure of the induced cometary magnetosphere that it delineated was close to theoretical predictions. While the strong draping of the magnetic field lines to form a magnetotail was anticipated, the structure of this magnetotail also indicated the existence of other predicted features. These included a weak shock or compression wave, an ionopause which at least partially impeded the penetration of the solar wind into the cometary ionosphere, and a magnetic barrier region where the magnetic field was piled up ahead of the ionopause. The inferred positions of these features enabled the estimation of the production rate of the neutrals from the nucleus (≈ 4×1028 mols/sec), as well as the strength of the coupling between the inflowing solar wind ions and the outflowing cometary neutrals.