The termination shock: 1979–1995

Abstract

We study the varying location, jump condition, and shock speed of the termination shock in 1979–1995 taking into account the effects of pickup protons. Pickup protons and neutral hydrogen are calculated using a hot hydrogen model. Plasma and magnetic field data from Voyagers over a 17‐year period from 1978 through 1994 are used as input. The steady state MHD equations are integrated to extrapolate input data from the Voyager trajectory to the upstream of the termination shock. This study continues to show that the location of the termination shock is anticorrelated with the sunspot number, moving inward or outward during the rising or declining phase of the solar cycle. We expect that this anticorrelation would repeat itself during the solar cycle 23 in an extension of this study beyond 1995, and the result can predict the Voyager crossing of the termination shock. If the average location of the termination shock is at 79 AU, the pickup proton effects reduce the average shock strength from 3.87 to 3.15 and reduce the average temperature ratio of the solar wind protons from 378 to 42.1. We use the empirical formula of Whang and Burlaga [1999] to calculate the postshock temperature of pickup protons, the average temperature ratio of pickup protons across the termination shock is ∼4.5.