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Title: The Formation of Magnetic Depletions and Flux Annihilation Due to Reconnection in the Heliosheath

Abstract

The misalignment of the solar rotation axis and the magnetic axis of the Sun produces a periodic reversal of the Parker spiral magnetic field and the sectored solar wind. The compression of the sectors is expected to lead to reconnection in the heliosheath (HS). We present particle-in-cell simulations of the sectored HS that reflect the plasma environment along the Voyager 1 and 2 trajectories, specifically including unequal positive and negative azimuthal magnetic flux as seen in the Voyager data. Reconnection proceeds on individual current sheets until islands on adjacent current layers merge. At late time, bands of the dominant flux survive, separated by bands of deep magnetic field depletion. The ambient plasma pressure supports the strong magnetic pressure variation so that pressure is anticorrelated with magnetic field strength. There is little variation in the magnetic field direction across the boundaries of the magnetic depressions. At irregular intervals within the magnetic depressions are long-lived pairs of magnetic islands where the magnetic field direction reverses so that spacecraft data would reveal sharp magnetic field depressions with only occasional crossings with jumps in magnetic field direction. This is typical of the magnetic field data from the Voyager spacecraft. Voyager 2 data reveal thatmore » fluctuations in the density and magnetic field strength are anticorrelated in the sector zone, as expected from reconnection, but not in unipolar regions. The consequence of the annihilation of subdominant flux is a sharp reduction in the number of sectors and a loss in magnetic flux, as documented from the Voyager 1 magnetic field and flow data.« less

Authors:
 [1];  [2];  [3];  [4]
  1. Department of Physics, the Institute for Physical Science and Technology and the Joint Space Institute, University of Maryland, College Park, MD 20742 (United States)
  2. Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD 20742 (United States)
  3. Astronomy Department, Boston University, MA 02215 (United States)
  4. Kavli Center for Astrophysics and Space Science, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
Publication Date:
OSTI Identifier:
22661273
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 837; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANNIHILATION; COMPRESSION; DENSITY; FLUCTUATIONS; HELIOSPHERE; LAYERS; LOSSES; MAGNETIC FIELDS; MAGNETIC FLUX; MAGNETIC ISLANDS; MAGNETIC RECONNECTION; PERIODICITY; PLASMA PRESSURE; SIMULATION; SOLAR WIND; SUN; TRAJECTORIES; VOYAGER SPACE PROBES

Citation Formats

Drake, J. F., Swisdak, M., Opher, M., and Richardson, J. D., E-mail: drake@umd.edu. The Formation of Magnetic Depletions and Flux Annihilation Due to Reconnection in the Heliosheath. United States: N. p., 2017. Web. doi:10.3847/1538-4357/AA6304.
Drake, J. F., Swisdak, M., Opher, M., & Richardson, J. D., E-mail: drake@umd.edu. The Formation of Magnetic Depletions and Flux Annihilation Due to Reconnection in the Heliosheath. United States. doi:10.3847/1538-4357/AA6304.
Drake, J. F., Swisdak, M., Opher, M., and Richardson, J. D., E-mail: drake@umd.edu. Fri . "The Formation of Magnetic Depletions and Flux Annihilation Due to Reconnection in the Heliosheath". United States. doi:10.3847/1538-4357/AA6304.
@article{osti_22661273,
title = {The Formation of Magnetic Depletions and Flux Annihilation Due to Reconnection in the Heliosheath},
author = {Drake, J. F. and Swisdak, M. and Opher, M. and Richardson, J. D., E-mail: drake@umd.edu},
abstractNote = {The misalignment of the solar rotation axis and the magnetic axis of the Sun produces a periodic reversal of the Parker spiral magnetic field and the sectored solar wind. The compression of the sectors is expected to lead to reconnection in the heliosheath (HS). We present particle-in-cell simulations of the sectored HS that reflect the plasma environment along the Voyager 1 and 2 trajectories, specifically including unequal positive and negative azimuthal magnetic flux as seen in the Voyager data. Reconnection proceeds on individual current sheets until islands on adjacent current layers merge. At late time, bands of the dominant flux survive, separated by bands of deep magnetic field depletion. The ambient plasma pressure supports the strong magnetic pressure variation so that pressure is anticorrelated with magnetic field strength. There is little variation in the magnetic field direction across the boundaries of the magnetic depressions. At irregular intervals within the magnetic depressions are long-lived pairs of magnetic islands where the magnetic field direction reverses so that spacecraft data would reveal sharp magnetic field depressions with only occasional crossings with jumps in magnetic field direction. This is typical of the magnetic field data from the Voyager spacecraft. Voyager 2 data reveal that fluctuations in the density and magnetic field strength are anticorrelated in the sector zone, as expected from reconnection, but not in unipolar regions. The consequence of the annihilation of subdominant flux is a sharp reduction in the number of sectors and a loss in magnetic flux, as documented from the Voyager 1 magnetic field and flow data.},
doi = {10.3847/1538-4357/AA6304},
journal = {Astrophysical Journal},
number = 2,
volume = 837,
place = {United States},
year = {Fri Mar 10 00:00:00 EST 2017},
month = {Fri Mar 10 00:00:00 EST 2017}
}
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