Voyager 2 High Energy Ions Near the Outward Moving Termination Shock

Abstract

We present results on the recurrence of High Energy Ions (HEIs) in the V2 data about 90 days after the initial sunward‐moving termination shock (TS) crossings of V2 in Aug.–Sept. 2007. We associate the HEIs in Nov.–Dec. 2007 with the outward motion of the TS or with a ripple in the TS so that the TS is again near V2. Comparisons of the timings of the recurrence of the HEI detections and the simultaneous V2 convective plasma, energetic particle, and magnetic field data indicate that the variations in all these V2 data sets are consistent with the TS re‐approach to V2 in Nov.–Dec. 2007. We use our three‐dimensional (3D) kinematic HAFSS model to investigate whether the timing of the arrival at V2 of the increase in solar wind dynamic pressure associated with the December 2006 solar events could have been responsible for the dynamic pressure pulse that moved the TS outward toward V2 ∼90 days after the initial TS crossings of V2. This explanation or, alternatively, a 3D solar wind inhomogeneity‐caused TS ripple (on the scale of ∼1 AU) could be viable scenarios to explain the recurrence of the HEIs in the V2 data in Nov.–Dec. 2007.