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| Titel |
Proton beam velocity distributions in an interplanetary coronal mass ejection |
| VerfasserIn |
E. Marsch, S. Yao, C.-Y. Tu |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 27, no. 2 ; Nr. 27, no. 2 (2009-02-19), S.869-875 |
| Datensatznummer |
250016421
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| Publikation (Nr.) |
 copernicus.org/angeo-27-869-2009.pdf |
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| Zusammenfassung |
| The plasma and magnetic-field instruments on the Helios 2
spacecraft, which was on 3 April 1979 located at 0.68 AU, detected
an interplanetary coronal mass ejection (ICME) that revealed
itself by the typical signature of magnetic field rotation. The
solar wind flow speed ranged between 400 and 500 km/s. We present
here some detailed proton velocity distributions measured within
the ICME. These cold distributions are characterized by an
isotropic core part with a low temperature, T≤105 K, but
sometimes reveal a broad and extended hot proton tail or beam
propagating along the local magnetic field direction. These beams
lasted only for about an hour and were unusual as compared with
the normal ICME protons distribution which were comparatively
isotropic. Furthermore, we looked into the velocity and field
fluctuations in this ICME and found signatures of Alfvén waves,
which might be related to the occurrence of the hot proton beams.
However, it cannot be excluded that the beam originated from the Sun. |
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