Draping of the Interstellar Magnetic Field over the Heliopause - A Passive Field Model

TL;DR

This paper presents an analytical model of how the interstellar magnetic field drapes around the heliopause, comparing it with observations from IBEX and Voyager 1 to support the secondary ENA model and heliopause crossing interpretations.

Contribution

It provides the first analytical solution for the draped magnetic field around the heliopause assuming a potential flow and weak magnetic field, linking theory with observations.

Findings

Qualitative agreement with IBEX ribbon observations

Support for Voyager 1 crossing the heliopause

Prediction of minimal magnetic field rotation for Voyager 2

Abstract

As the local interstellar plasma flows past our heliosphere, it is slowed and deflected around the magnetic obstacle of the heliopause. The interstellar magnetic field, frozen into this plasma, then becomes draped around the heliopause in a characteristic manner. We derive the analytical solution for this draped magnetic field in the limit of weak field intensity, assuming an ideal potential flow around the heliopause, which we model as a Rankine half-body. We compare the structure of the model magnetic field with observed properties of the IBEX ribbon and with in situ observations at the Voyager 1 spacecraft. We find reasonable qualitative agreement, given the idealizations of the model. This agreement lends support to the secondary ENA model of the IBEX ribbon and to the interpretation that Voyager 1 has crossed the heliopause. We also predict that the magnetic field measured by Voyager 2 after it crosses the heliopause will not be significantly rotated away from the direction of the undisturbed interstellar field.