Coronal Jet Collimation by Nonlinear Induced Flows
| Autor: | S. M. Hejazi, S. Vasheghani Farahani |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Physics
010504 meteorology & atmospheric sciences Flux tube Astronomy and Astrophysics Mechanics Plasma Ponderomotive force 01 natural sciences Magnetic field Physics::Fluid Dynamics Alfvén wave Physics::Plasma Physics Space and Planetary Science Physics::Space Physics 0103 physical sciences Magnetic tension force Magnetohydrodynamic drive Shear flow 010303 astronomy & astrophysics 0105 earth and related environmental sciences |
| Zdroj: | The Astrophysical Journal. 844:148 |
| ISSN: | 1538-4357 |
| DOI: | 10.3847/1538-4357/aa7da5 |
| Popis: | Our objective is to study the collimation of solar jets by nonlinear forces corresponding to torsional Alfven waves together with external forces. We consider a straight, initially non-rotating, untwisted magnetic cylinder embedded in a plasma with a straight magnetic field, where a shear between the internal and external flows exists. By implementing magnetohydrodynamic theory and taking into account the second-order thin flux tube approximation, the balance between the internal nonlinear forces is visualized. The nonlinear differential equation containing the ponderomotive, magnetic tension, and centrifugal forces in the presence of the shear flow is obtained. The solution presents the scale of influence of the propagating torsional Alfven wave on compressive perturbations. Explicit expressions for the compressive perturbations caused by the forces connected to the torsional Alfven wave show that, in the presence of a shear flow, the magnetic tension and centrifugal forces do not cancel each other's effects as they did in its absence. This shear flow plays in favor of the magnetic tension force, resulting in a more efficient collimation. Regarding the ponderomotive force, the shear flow has no effect. The phase relations highlight the interplay of the shear flow and the plasma-β. As the shear flow and plasma-β increase, compressive perturbation amplitudes emerge. We conclude that the jet collimation due to the torsional Alfven wave highly depends on the location of the jet. The shear flow tightens the collimation as the jet elevates up to the solar corona. |
| Databáze: | OpenAIRE |
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