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The Solar Wind in the Outer Heliosphere

Richardson, J. D. and Stone, E. C. (2009) The Solar Wind in the Outer Heliosphere. In: From the Outer Heliosphere to the Local Bubble: Comparisons of New Observations with Theory. Space Science Series of ISSI. No.31. Springer , pp. 7-20. ISBN 978-1-4419-0246-7.

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The solar wind evolves as it moves outward due to interactions with both itself and with the circum-heliospheric interstellar medium. The speed is, on average, constant out to 30 AU, then starts a slow decrease due to the pickup of interstellar neutrals. These neutrals reduce the solar wind speed by about 20% before the termination shock (TS). The pickup ions heat the thermal plasma so that the solar wind temperature increases outside 20–30 AU. Solar cycle effects are important; the solar wind pressure changes by a factor of 2 over a solar cycle and the structure of the solar wind is modified by interplanetary coronal mass ejections (ICMEs) near solar maximum. The first direct evidences of the TS were the observations of streaming energetic particles by both Voyagers 1 and 2 beginning about 2 years before their respective TS crossings. The second evidence was a slowdown in solar wind speed commencing 80 days before Voyager 2 crossed the TS. The TS was a weak, quasi-perpendicular shock which transferred the solar wind flow energy mainly to the pickup ions. The heliosheath has large fluctuations in the plasma and magnetic field on time scales of minutes to days.

Item Type:Book Section
Related URLs:
URLURL TypeDescription ItemJournal Article
Richardson, J. D.0000-0003-4041-7540
Stone, E. C.0000-0002-2010-5462
Additional Information:© Springer Science+Business Media, BV 2008. This work was supported by NASA; at MIT by NASA contract 959203 from JPL to MIT and NASA grant NAG5-8947. Originally published in the journal Space Science Reviews, Volume 143, Nos 1–4, 7–20.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Subject Keywords:Solar wind; Termination shock; Heliosheath; Heliopause; Pickup ions; Interstellar neutral atoms; Anomalous cosmic rays
Series Name:Space Science Series of ISSI
Issue or Number:31
Record Number:CaltechAUTHORS:20190927-135404002
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:98910
Deposited By: George Porter
Deposited On:30 Sep 2019 14:26
Last Modified:16 Nov 2021 17:42

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