Astrophysics and Space Sciences Transactions www.astrophys-space-sci-trans.net 1810-6528 1810-6536 2 1 2006 10.5194/astra-2-19-2006 http://www.astrophys-space-sci-trans.net/2/19/2006/ http://www.astrophys-space-sci-trans.net/2/19/2006/astra-2-19-2006.html http://www.astrophys-space-sci-trans.net/2/19/2006/astra-2-19-2006.pdf 19 25 2006-02-07 Heating of the solar wind in the outer heliosphere S. V. Chalov D. B. Alexashov H.-J. Fahr Institute for Problems in Mechanics of the Russian Academy of Sciences, Pr. Vernadskogo 101-1, 119526 Moscow, Russia Institute for Astrophysics and Extraterrestrial Research of the University of Bonn, Auf dem Hügel 71, 53121 Bonn, Germany Small-scale Alfvènic turbulence in the outer heliosphere is mainly determined by a source which is connected with the instability of the initially highly anisotropic velocity distribution of interstellar pick-up protons. The main portion of the generated turbulent energy is subsequently absorbed by the pick-up protons themselves due to the cyclotron-resonant interaction between waves and particles. A small fraction of this energy can be transferred to solar wind protons resulting in their heating. The heating is more efficient in the high-speed solar wind.