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Record Details

Record 8 of 18060
The Magnetic Field in the Outer Heliosphere
Author and Affiliation:
Suess, S. T.(National Space Science and Technology Center, Huntsville, AL, United States)
Abstract: One of the great achievements of Parker was the prediction that the solar magnetic field would be drawn into Archimedian spirals as it is carried away from the Sun by the solar wind. This prediction has been amply confirmed by many in situ measurements in the intervening four decades. But, Parker made his prediction for a solar wind that expands into infinite space while we now know that the local interstellar medium (LISM) is far from empty and, in fact, confines the solar wind to a finite volume, known as the heliosphere, that extends to approximately 100 AU in the upstream direction (the solar system is moving through the LISM). Voyagers 1/2, presently at -80 AU, are approaching the upstream boundaries of the heliosphere and returning data on the properties of the magnetic field. This is important for understanding how galactic cosmic rays (GCRs) reach the Earth. Voyagers show that the IMF at 10-80 AU behaves much as Parker predicted - with two important exceptions. This is not surprising since the field is essentially passively advected by the solar wind out to 80 AU. But, new models say that nearer the heliosphere boundaries the field plays a major role in the solar wind-LISM interaction. However, of the many physical ingredients that constitute the outer heliosphere, the magnetic field poses some of the most interesting and difficult numerical modeling problems. Presently, only a few results have been published and much remains to be done. Here I will summarize the expected and measured behavior of the magnetic field at 80 AU. Then I will describe modeling predictions beyond 80 AU: magnetic "tornadoes", polarity envelopes, the Axford-Cranfill effect, inner and outer magnetic walls and more. I will also list what I believe to be important new modeling objectives. Finally, I will speculate on what is happening with the magnetic field near the nose of the heliosphere. My conclusion is that models of GCR modulation rarely incorporate even crudely realistic magnetic fields so it is a wonder that they are as successful as they are and no surprise that there are still important discrepancies between GCR modulation observations and the models.
Publication Date: Jan 01, 2004
Document ID:
20040068124
(Acquired Jun 04, 2004)
Subject Category: ASTROPHYSICS
Document Type: Preprint
Meeting Information: Arcetri Astrophysical Observatory Presentation; 29 Apr. 2004; Florence; Italy
Financial Sponsor: NASA Marshall Space Flight Center; Huntsville, AL, United States
Organization Source: NASA Marshall Space Flight Center; Huntsville, AL, United States
Description: 1p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: HELIOSPHERE; SOLAR MAGNETIC FIELD; MAGNETIC FIELDS; SUN; MATHEMATICAL MODELS; FINITE VOLUME METHOD; IN SITU MEASUREMENT; VOYAGER 1 SPACECRAFT; INTERSTELLAR MATTER; GALACTIC COSMIC RAYS; SOLAR WIND
Availability Source: Other Sources
Availability Notes: Abstract Only
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