Voyager 2 Observations Near the Heliopause

John D. Richardson,Leonard F. Burlaga,John W. Belcher,Edward C. Stone,Alan C. Cummings,Robert B. Decker,Merav Opher

doi:10.1088/1742-6596/1620/1/012016

Abstract

This paper discusses plasma characteristics in the heliosheath region before the heliopause (HP), at the HP, and in the very local interstellar medium (VLISM). The Voyager 2 (V2) HP was a sharp boundary where the radial plasma currents went to background levels. The radial flow speeds derived from 53-85 keV (V1) and 28-43 keV (V2) ion data decreased about 2 years (8 AU) before the HP at V1 and V2. A speed decrease was not observed by the V2 plasma instrument until 160 days (1.5 AU) before the HP crossing when V2 entered the plasma boundary layer where the plasma density and 28-43 keV ion intensity increased. We determine the HP orientation based on the plasma flow and magnetic field data and show these observations are consistent with models predicting a blunt HP. Variations are observed in the currents observed in the VLISM; roll data from this region clearly show the plasma instrument observes the interstellar plasma and may be consistent with larger than expected VLISM temperatures near the HP.

Highlights

Voyager 2 (V2) crossed the heliopause (HP) on Nov. 5 2018 when it was 119 AU from the Sun at a heliolatitude of 31° S [1,2,3,4], close to distance the predicted by Washimi et al [5]
The Voyager 2 (V2) HP was a sharp boundary where the radial plasma currents went to background levels
Variations are observed in the currents observed in the very local interstellar medium (VLISM); roll data from this region clearly show the plasma instrument observes the interstellar plasma and may be consistent with larger than expected VLISM temperatures near the HP

Summary

Introduction

Voyager 2 (V2) crossed the heliopause (HP) on Nov. 5 2018 when it was 119 AU from the Sun at a heliolatitude of 31° S [1,2,3,4], close to distance the predicted by Washimi et al [5]. The Voyager 1 (V1) plasma instrument failed in 1980, so V2 provides the first plasma data from the HP boundary regions, at the HP, and in the very local interstellar medium (VLISM) [6]. V1 crossed the HP in August 2012 at 121.7 AU [7,8,9,10] and in 2020 passed 150 AU. This paper describes the V2 observations near the HP and compares them with those from V1

HP Overview

Plasma flows and the HP orientation

Plasma Boundary Layer and Magnetic Barrier

Plasma in the VLISM

Findings

Summary