تقرير
Heliospheric Evolution of Magnetic Clouds
| العنوان: | Heliospheric Evolution of Magnetic Clouds |
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| المؤلفون: | Vršnak, Bojan, Amerstorfer, Tanja, Dumbović, Mateja, Leitner, Martin, Veronig, Astrid M., Temmer, Manuela, Möstl, Christian, Amerstorfer, Ute V., Farrugia, Charles J., Galvin, Antoinette B. |
| سنة النشر: | 2019 |
| المجموعة: | Astrophysics Physics (Other) |
| مصطلحات موضوعية: | Astrophysics - Solar and Stellar Astrophysics, Physics - Space Physics |
| الوصف: | Interplanetary evolution of eleven magnetic clouds (MCs) recorded by at least two radially aligned spacecraft is studied. The in situ magnetic field measurements are fitted to a cylindrically symmetric Gold-Hoyle force-free uniform-twist flux-rope configuration. The analysis reveals that in a statistical sense the expansion of studied MCs is compatible with self-similar behavior. However, individual events expose a large scatter of expansion rates, ranging from very weak to very strong expansion. Individually, only four events show an expansion rate compatible with the isotropic self-similar expansion. The results indicate that the expansion has to be much stronger when MCs are still close to the Sun than in the studied 0.47 - 4.8 AU distance range. The evolution of the magnetic field strength shows a large deviation from the behavior expected for the case of an isotropic self-similar expansion. In the statistical sense, as well as in most of the individual events, the inferred magnetic field decreases much slower than expected. Only three events show a behavior compatible with a self-similar expansion. There is also a discrepancy between the magnetic field decrease and the increase of the MC size, indicating that magnetic reconnection and geometrical deformations play a significant role in the MC evolution. About half of the events show a decay of the electric current as expected for the self-similar expansion. Statistically, the inferred axial magnetic flux is broadly consistent with it remaining constant. However, events characterized by large magnetic flux show a clear tendency of decreasing flux. Comment: 64 pages, 10 figures |
| نوع الوثيقة: | Working Paper |
| DOI: | 10.3847/1538-4357/ab190a |
| URL الوصول: | http://arxiv.org/abs/1904.08266 |
| رقم الأكسشن: | edsarx.1904.08266 |
| قاعدة البيانات: | arXiv |
| DOI: | 10.3847/1538-4357/ab190a |
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