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Astron. Astrophys. 354, 321-327 (2000)

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6. Conclusions

From the analysis of the gyrotropic motion of ions that have been accelerated by a streaming magnetized flow it has been found that their longer stay near the apex of their cycloidal trajectories produces a non-uniform distribution with a distinct particle accumulation along regions that resemble filamentary structures. For uniform speed flows the regions where there is an accumulation of gyrating ions are parallel to each other and become equally spaced as is shown in Fig. 6. In the presence of a velocity shear the structures acquire a slanted orientation forming different angles with respect to the direction of the flow. In this case the regions where there is an enhanced particle population become oriented in the pattern shown in Fig. 8 and is similar to the distribution of plasma tail rays seen in cometary wakes. The particle distribution reflects a steady state configuration and is not intended to describe the time evolution of each structure.

An analytical solution was derived for the case in which the ion source in infinite and the magnetic field is on the plane perpendicular to the velocity shear. With this geometry it is possible to provide a more accurate interpretation of the conditions seen in the ICE observations in comet Giacobini-Zinner.

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© European Southern Observatory (ESO) 2000

Online publication: January 31, 2000