The Impact of Kinetic Neutrals on the Heliotail
Abstract
The shape of the heliosphere is thought to resemble a long, comet tail, however, recently it has been suggested that the heliosphere is tailless with a two-lobe structure. The latter study was done with a three-dimensional (3D) magnetohydrodynamic code, which treats the ionized and neutral hydrogen atoms as fluids. Previous studies that described the neutrals kinetically claim that this removes the two-lobe structure of the heliosphere. In this work, we use the newly developed Solar-wind with Hydrogen Ion Exchange and Large-scale Dynamics (SHIELD) model. SHIELD is a self-consistent kinetic-MHD model of the outer heliosphere that couples the MHD solution for a single plasma fluid from the BATS-R-US MHD code to the kinetic solution for neutral hydrogen atoms solved by the Adaptive Mesh Particle Simulator, a 3D, direct simulation Monte Carlo model that solves the Boltzmann equation. We use the same boundary conditions as our previous simulations using multi-fluid neutrals to test whether the two-lobe structure of the heliotail is removed with a kinetic treatment of the neutrals. Our results show that despite the large difference in the neutral hydrogen solutions, the two-lobe structure remains. These results are contrary to previous kinetic-MHD models. One such model maintains a perfectly ideal heliopause and does not allow for communication between the solar wind and interstellar medium. This indicates that magnetic reconnection or instabilities downtail play a role for the formation of the two-lobe structure.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 2021
- DOI:
- 10.3847/1538-4357/abc953
- Bibcode:
- 2021ApJ...906...37M
- Keywords:
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- Heliosphere;
- Heliopause;
- Heliosheath;
- Termination shock;
- Stellar wind bubbles;
- Solar wind termination;
- Magnetohydrodynamical simulations;
- Magnetohydrodynamics;
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- 707;
- 710;
- 1690;
- 1635;
- 1535;
- 1966;
- 1964