Journal cover Journal topic
Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 32, 651-657, 2014
© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.
Regular paper
17 Jun 2014
Mirror mode structures near Venus and Comet P/Halley
D. Schmid1, M. Volwerk1, F. Plaschke1, Z. Vörös1, T. L. Zhang1,2, W. Baumjohann1, and Y. Narita1 1Space Research Institute, Austrian Academy of Sciences, 8042 Graz, Austria
2University of Science and Technology of China, Hefei, China
Abstract. In this paper, we study where mirror mode structures are generated near unmagnetized solar system bodies (Venus and comet P/Halley measured in situ by Venus Express and Giotto). To estimate the location of the mirror mode source region at Venus, we apply a turbulent diffusion model of mirror mode structures, which has already been successfully tested in planetary magnetosheaths (Earth, Jupiter, Saturn). It enables us to estimate the distance between the measured location of the mirror mode and the origin of the mirror mode structure through the mirror mode size. We find that the scenario of mirror mode excitation at the bow shock with subsequent convection and diffusion downstream to the magnetopause is valid for Venus. In the cometary case, however, we find that the size of the mirror mode structure is comparable to the gyroradius of water group ions. This suggests local production of mirror mode structures in the cometary magnetosheath, most likely through fresh ion pickup, as opposed to the convection and diffusion mechanism at Venus.

Citation: Schmid, D., Volwerk, M., Plaschke, F., Vörös, Z., Zhang, T. L., Baumjohann, W., and Narita, Y.: Mirror mode structures near Venus and Comet P/Halley, Ann. Geophys., 32, 651-657,, 2014.
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