| 1. |
- Alfvén, Hannes, et al.
(författare)
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Voyager saturnian ring measurements and the early history of the solar-system
- 1986
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Ingår i: Planetary and Space Science. - : Elsevier BV. - 0032-0633 .- 1873-5088. ; 34:2, s. 145-154
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Tidskriftsartikel (refereegranskat)abstract
- The mass distribution in the Saturnian ring system is investigated and compared with predictions from the plasma cosmogony. According to this theory, the matter in the rings has once been in the form of a magnetized plasma, in which the gravitation is balanced partly by the centrifugal force and partly by the electromagnetic forces. As the plasma is neutralized, the electromagnetic forces disappear and the matter can be shown to fall in to of the original saturnocentric distance. This causes the so called “cosmogonic shadow effect”, which has been demonstrated earlier for the asteroidal belt and in the large scale structure of the Saturnian ring system.The relevance of the cosmogonic shadow effect is investigated for parts of the fine structures of the Saturnian ring system. It is shown that many structures of the present ring system can be understood as shadows and antishadows of cosmogonic origin. These appear in the form of double rings centered around a position a factor 0.64 (slightly less than) closer to Saturn than the causing feature. Voyager data agree with an accuracy better than 1%.
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| 2. |
- Fälthammar, Carl-Gunne
(författare)
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Electric fields in the magnetosphere- a review
- 1989
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Ingår i: Planetary and Space Science. - : Elsevier BV. - 0032-0633. ; 37, s. 899-914
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Tidskriftsartikel (refereegranskat)abstract
- The satellites S3-3, GEOS-1, GEOS-2, ISEE-1 and Viking have extended direct measurements of electric fields to include the outer regions of the magnetosphere. The measurements confirm some of the theoretically expected properties of the electric fields. More importantly, they also reveal unexpected features and a high degree of complexity and variability. The existence of a magnetospheric dawn-dusk electric field has been confirmed in an average sense. However, the actual field exhibits large spatial and temporal variations, including strong fields of inductive origin. At the magnetopause the average (dawn-dusk directed) tangential electric field component is typlcally obscured by irregular fluctuations of larger amplitude. The magnetic field-aligned component of the electric field, which is of particular importance for ionosphere-magnetosphere coupling and for auroral acceleration is even now very difficult to measure directly. However, the data from electric field measurements provide further support for the conclusion, based on a variety of evidence, that a non-vanishing magnetic field-aligned electric field exists in the auroral acceleration region. © 1989.
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