A time dependent model for spicule flow |
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| Authors: | S S Hasan P Venkatakrishnan |
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| Institution: | (1) Indian Institute of Astrophysics, 560 034 Bangalore, India |
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| Abstract: | A time dependent model for the flow of gas in a spicule is studied. In this model, the flow occurs in a magnetic flux sheath. Starting from hydrostatic equilibrium, the flux sheath is allowed to collapse normal to itself. The collapse induces a flow of gas along the magnetic field and this flow is identified as a spicule. A variety of sheath geometries and velocity patterns for the normal flow have been studied. It is observed that a large curvature in the field geometry and a large initial value for the normal flow are necessary to achieve spicule-like velocities. The duration for which a large velocity of normal flow is required is much shorter than the average lifetime of a spicule. It is proposed that the initial rapid collapse occurs during an  impulsive spicule phase and it is the subsequent gradual relaxation of the flow which is observed as a spicule. |
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