Termination Shock Measured by Voyagers and IBEX

Abstract

Abstract Our heliosphere’s innermost boundary—the termination shock—slows and heats the supersonic solar wind and energizes anomalous cosmic rays (ACRs). We show that in addition to their termination shock crossings, the Voyager 1 and 2 spacecraft measurements identify additional points on the termination shock when they magnetically disconnect from the ACR source. These four points define a spherical approximation of the termination shock with radius 117 au, offset ∼32 au tailward, ∼27 au north, and ∼12 au to the port side of the Sun. Interstellar Boundary Explorer (IBEX) spacecraft observations independently confirm these general offsets, with the closest region of the termination shock ∼ 20° south of the interstellar inflow direction and a minimum distance ∼74 au. The maximum distance is ∼161 au, consistent with required ACR acceleration times. Thus, Voyager and IBEX spacecraft observations have directly revealed the global size and location of our heliosphere’s termination shock for the first time.