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| Titel |
3-D numerical simulations of coronal loops oscillations |
| VerfasserIn |
M. Selwa, L. Ofman |
| 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. 10 ; Nr. 27, no. 10 (2009-10-13), S.3899-3908 |
| Datensatznummer |
250016678
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| Publikation (Nr.) |
 copernicus.org/angeo-27-3899-2009.pdf |
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| Zusammenfassung |
| We present numerical results of 3-D MHD model of a dipole active
region field containing a loop with a higher density than its
surroundings. We study different ways of excitation of vertical kink
oscillations by velocity perturbation: as an initial condition, and
as an impulsive excitation with a pulse of a given position,
duration, and amplitude. These properties are varied in the
parametric studies. We find that the amplitude of vertical kink
oscillations is significantly amplified in comparison to horizontal
kink oscillations for exciters located centrally (symmetrically)
below the loop, but not if the exciter is located a significant
distance to the side of the loop. This explains why the pure
vertical kink mode is so rarely observed in comparison to the
horizontally polarized one.
We discuss the role of curved magnetic field lines and the pulse
overlapping at one of the loop's footpoints in 3-D active regions
(AR's) on the excitation and the damping of slow standing waves. We
find that footpoint excitation becomes more efficient in 3-D curved
loops than in 2-D curved arcades and that slow waves can be excited
within an interval of time that is comparable to the observed one
wave-period due to the combined effect of the pulse inside and
outside the loop. Additionally, we study the effect of AR topology
on the excitation and trapping of loop oscillations. We find that a
perturbation acting directly on a single loop excites oscillations,
but results in an increased leakage compared to excitation of
oscillations in an AR field by an external source. |
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