Thermal instability and transport effects in comets |
| |
Authors: | A. S. Sharma G. M. Milikh |
| |
Affiliation: | (1) Department of Astronomy, University of Maryland, College Park, Maryland |
| |
Abstract: | The localized ion density depletion region observed at comet Halley can be understood in terms of a thermal instability of the cometary plasma due to the excitation of rotational and vibrational levels of water molecules. The electron energy losses due to these processes peak near 4000 K and at higher temperatures a localized cooling leads to the thermal instability due to the increased radiation loss. The resulting increase in recombination leads to the ion density depletion and the estimates for this depletion at comet Halley agree with the observations. The transport effects at the density depletion region due to the diffusion and thermal conductivity are found have time scales larger than the instability time scale and does not affect the formation of the depletion region. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |