The Two-Lobe Structure of the Heliosphere Persists in the SHIELD Model, a K-MHD Model of the Outer Heliosphere
Abstract
The canonical view of the shape of the heliosphere resembles a long comet tail, however, our research group at BU, led by Dr. Merav Opher, has suggested that the heliosphere is tailless with a two-lobe structure. This study was done with a state-of-the-art 3D magnetohydrodynamic (MHD) code that treats the ionized and neutral hydrogen atoms as fluids. Previous studies that have described the neutrals kinetically have claimed that this removes the two-lobe structure of the heliosphere. In this work, we will use the newly developed Solar-wind with Hydrogen Ion Exchange and Large-scale Dynamics (SHIELD) model, a self-consistent kinetic-MHD model of the outer heliosphere. The SHIELD model couples the Outer Heliosphere (OH) and Particle Tracker (PT) components within the Space Weather Modeling Framework (SWMF). The OH component utilizes the Block-Adaptive Tree Solarwind Roe-type Upwind Scheme (BATS-R-US) MHD code, a highly parallel, 3D, and block-adaptive solver. The PT component is based on the Adaptive Mesh Particle Simulator (AMPS) model, a 3D, direct simulation Monte Carlo model that solves the Boltzmann equation to model the neutral distribution function throughout the domain. The SHIELD model couples the MHD solution for a single plasma fluid to the kinetic solution from for neutral hydrogen atoms streaming through the system. We use the same boundary conditions as Opher et al. (2015), the seminal work on the two-lobe structure, within the SHIELD model to test whether the two-lobe structure of the heliotail is removed. Our results show that despite the large difference in the neutral solution between the fluid and kinetic treatment of the neutral hydrogen, the two-lobe structure remains even when the neutral hydrogen atoms are modeled kinetically. These results are contrary to Izmodenov et al (2018), whose model maintains a perfectly ideal heliopause and does not allow for communication between the solar wind and interstellar medium . This indicates that magnetic reconnection downtail and/or instabilities play a crucial role for the formation of the two-lobe structure.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSH51B..07M
- Keywords:
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- 7845 Particle acceleration;
- SPACE PLASMA PHYSICS;
- 7851 Shock waves;
- SPACE PLASMA PHYSICS;
- 7859 Transport processes;
- SPACE PLASMA PHYSICS;
- 7863 Turbulence;
- SPACE PLASMA PHYSICS