Abstract
We study the temperature of electrons advected with the solar wind to large solar distances far beyond 1 AU. Almost nothing is known about the thermodynamics of these electrons from in-situ plasma observations at these distances, and usually it is tacitly assumed that electrons, due to adiabatic behaviour and vanishing heat conduction, rapidly cool off to very low temperatures at larger distances. In this article we show, however, that electrons on their way to large distances undergo non-adiabatic interactions with travelling shocks and solar-wind bulk-velocity jumps and thereby are appreciably heated. Examining this heating process on an average statistical basis, we find that solar-wind electrons first cool down to a temperature minimum, which depending on the occurrence frequency of bulk velocity jumps is located between 3 and 6 AU, but beyond this the lowest electron temperature again starts to increase with increasing solar distance, finally achieving temperatures of about 7×104 K to 7×105 K at the location of the termination shock. Hence these electrons are unexpectedly shown to play an important dynamical role in structuring this shock and in determining the downstream plasma properties.
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Achatz, U., Dröge, W., Schlickeiser, R., Wibberenz, G.: 1993, J. Geophys. Res. 98, 13261.
Alexandrov, A.F., Bogdankevich, L.S., Rukhadze, A.A.: 1984, Principles of Plasma Electrodynamics, Springer Series in Electrophysics 9, Springer, Berlin.
Burlaga, L.F.: 1971, Space Sci. Rev. 12, 600.
Chashei, I.V., Fahr, H.J.: 2000, Astron. Astrophys. 363, 295.
Chashei, I.V., Fahr, H.J., Lay, G.: 2001, In: Scherer, K., Fichtner, H., Fahr, H.J., Marsch, E. (eds.) The Outer Heliosphere: The Next Frontiers, COSPAR Colloquia Series 11, Pergamon Press, Elmsford.
Chashei, I.V., Fahr, H.J., Lay, G.: 2005, Solar Phys. 226, 167.
Chen, F.F.: 1984, Plasma Physics, Plenum Press, New York.
Fahr, H.J.: 2007, Ann. Geophys. 25, 2649.
Fahr, H.J., Chashei, I.V.: 2002, Astron. Astrophys. 395, 991.
Fahr, H.J., Fichtner, H.: 2011, Astron. Astrophys. 533, A92.
Fahr, H.J., Fichtner, H.: 2012, Ann. Geophys. 30, 1315.
Fahr, H.J., Siewert, M., Chashei, I.V.: 2012, Astrophys. Space Sci. 341, 265.
Feldman, W.C., Asbridge, J.R., Bame, S.J., Montgomery, M.D., Gary, S.P.: 1975, J. Geophys. Res. 80, 4181.
Gary, S.P., Scime, E.E., Philipps, J.L., Feldman, W.C.: 1994, J. Geophys. Res. 99, 23391.
McComas, D.J., Bame, S.J., Feldman, W.C., Gosling, J.T., Phillips, J.L.: 1992, Geophys. Res. Lett. 19, 1291.
Pilipp, W.G., Miggenrieder, H., Mühlhäuser, K.H., Rosenbauer, H., Schwenn, R.: 1987, J. Geophys. Res. 92, 1103.
Schlickeiser, R., Dung, R., Jaeckel, U.: 1991, Astron. Astrophys. 242, L5.
Scholer, M., Matsukiyo, S.: 2004, Ann. Geophys. 22, 2345.
Scime, E.E., Bame, S.J., Feldman, W.C., Gary, S.P., Pilipps, J.L.: 1994, J. Geophys. Res. 99, 23401.
Spitzer, L. Jr.: 1969, Physics of Fully Ionized Gases, Addison Wesley, Reading.
Verscharen, D., Fahr, H.J.: 2008, Astron. Astrophys. 487, 723.
Acknowledgements
This work was partially supported by the Program “Fundamental problems of the solar system research” by the Russian Academy of Sciences and partially by the Russian/German bi-national cooperation grant 436 RUS 113/110/0-4 sponsored by the Deutsche Forschungsgemeinschaft DFG and the Russian Science Foundation RFFI.
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Chashei, I.V., Fahr, H.J. On Solar-Wind Electron Heating at Large Solar Distances. Sol Phys 289, 1359–1370 (2014). https://doi.org/10.1007/s11207-013-0403-8
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DOI: https://doi.org/10.1007/s11207-013-0403-8