Workshop Participants (8-12 November 2021)

The initial reconnaissance of the outer heliosphere and local interstellar medium (LISM) with in situ measurements (Voyagers 1 and 2), remote sensing of energetic neutral atoms (ENAs) (IBEX and CASSINI) and hydrogen (Voyager and SOHO), and measurements of interstellar dust in the heliosphere (Ulysses) is complete. This workshop will review the heliosphere’s interaction with the LISM. The last ISSI workshops on similar topics were ‘’Cosmic rays in the Heliosphere’’ in April 2010 and ‘’From the Outer Heliosphere to the Local Bubble’’ in Oct. 2007. Since then major progress has been made. Both Voyager spacecraft crossed the heliopause boundary region and entered the LISM. Before the HP crossing, Voyager 2 observed a solar cycle of variation in the heliosheath and revealed very different plasma flows and particle variations than observed at V1.  ENA measurements from IBEX and CASSINI also span nearly a solar cycle. Modeling has shown the connection between the ENA and heliosheath particles that are their source and plays major roles in studies of the heliospheric shape, instabilities, and particle distributions.

Numerous questions still remain. Is the heliospheric tail long or short? What is the role of reconnection in producing the energetic particle profiles and energies in the heliosheath? Why was the heliosheath so narrow in the V1 direction? Why are plasma flows and particle intensities in the heliosheath so different at V1 and V2? Why does the heliopause structure differ at V1 and V2? How is the IBEX ribbon formed? The workshop will discuss these and other issues and proposed solutions.

The purpose of this is to produce the first ISSI reference work describing the complete heliosphere, including the heliopause and the effects of the heliosphere on the LISM.The workshop will cover observations and modeling and highlight what has been learned and what is still not understand. Although emphasis will be on the results of the past decade, the full interaction from pickup ions to the termination shock to the LISM will be covered with the goal of making this a complete reference.


The Workshop will cover the following main themes:

  • In situ observations
  • Remote UV and energetic neutral atom observations
  • Modeling of the heliosphere/LISM interaction
  • The structure of the heliosphere
  • Time dependence in the heliosphere
  • Future directions for observations and modeling