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Low Density Drivers of Strong Interplanetary Shocks

Published online by Cambridge University Press:  12 April 2016

A. Hewish*
Affiliation:
Mullard Radio Astronomy Observatory, Cavendish Laboratory, Madingley Road, Cambridge CBS OHE, U.K.

Abstract

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The theory that most, if not all, interplanetary shocks are caused by coronal mass ejections (CMEs) faces serious problems in accounting for the strongest shocks. The difficulties include (i) a remarkable absence of very strong shocks during solar maximum 1980 when CMEs were prolific, (ii) unrealistic initial speeds near the Sun for impulsive models, (iii) the absence of rarefaction zones behind the shocks and (iv) sustained high speed flows following shocks which are not easily explained as consequences of CME eruptions. Observations of the proton temperature near 1 AU indicate that strong shock drivers have properties similar to high speed streams emitted by coronal holes. Eruptions of fast solar wind from coronal holes influenced by solar activity can explain the occurrence of the strongest interplanetary shocks.

Type
Origin of Solar and Interplanetary Transients
Copyright
Copyright © Kluwer 1997

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