IS THE MAGNETIC FIELD IN THE HELIOSHEATH LAMINAR OR A TURBULENT SEA OF BUBBLES?

Journal Article · Fri Jun 10 00:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/734/1/71· OSTI ID:21576653

Opher, M ^[1]; Drake, J F ^[2]; Swisdak, M; Schoeffler, K M ^[3]; Richardson, J D ^[4]; Decker, R B ^[5]; Toth, G ^[6]

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1. Astronomy Department, Boston University, Boston, MA (United States)
2. Department of Physics and the Institute for Physical Science and Technology, University of Maryland, College Park, MD (United States)
3. Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD (United States)
4. Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA (United States)
5. John Hopkins Applied Physics Laboratory, Laurel, MD (United States)
6. University of Michigan, Ann Arbor, MI (United States)

All current global models of the heliosphere are based on the assumption that the magnetic field in the heliosheath, in the region close to the heliopause (HP), is laminar. We argue that in that region the heliospheric magnetic field is not laminar but instead consists of magnetic bubbles. We refer to it as the bubble-dominated heliosheath region. Recently, we proposed that the annihilation of the 'sectored' magnetic field within the heliosheath as it is compressed on its approach to the HP produces anomalous cosmic rays and also energetic electrons. As a product of the annihilation of the sectored magnetic field, densely packed magnetic islands (which further interact to form magnetic bubbles) are produced. These magnetic islands/bubbles will be convected with ambient flows as the sector region is carried to higher latitudes filling the heliosheath. We further argue that the magnetic islands/bubbles will develop upstream within the heliosheath. As a result, the magnetic field in the heliosheath sector region will be disordered well upstream of the HP. We present a three-dimensional MHD simulation with very high numerical resolution that captures the north-south boundaries of the sector region. We show that due to the high pressure of the interstellar magnetic field a north-south asymmetry develops such that the disordered sectored region fills a large portion of the northern part of the heliosphere with a smaller extension in the southern hemisphere. We suggest that this scenario is supported by the following changes that occurred around 2008 and from 2009.16 onward: (1) the sudden decrease in the intensity of low energy electrons (0.02-1.5 MeV) detected by Voyager 2, (2) a sharp reduction in the intensity of fluctuations of the radial flow, and (3) the dramatic differences in intensity trends between galactic cosmic ray electrons (3.8-59 MeV) at Voyager 1 and 2. We argue that these observations are a consequence of Voyager 2 leaving the sector region of disordered field during these periods and crossing into a region of unipolar laminar field.

• OSTI ID: 21576653
• Journal Information: Astrophysical Journal, Vol. 734, Issue 1; Other Information: DOI: 10.1088/0004-637X/734/1/71; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ANNIHILATION
BUBBLES
HELIOSPHERE
INTERSTELLAR MAGNETIC FIELDS
MAGNETIC ISLANDS
MAGNETOHYDRODYNAMICS
SIMULATION
THREE-DIMENSIONAL CALCULATIONS
ATMOSPHERES
FLUID MECHANICS
HYDRODYNAMICS
INTERACTIONS
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC FIELDS
MECHANICS
PARTICLE INTERACTIONS
SOLAR ATMOSPHERE
STELLAR ATMOSPHERES