Spicule is an elongated projection of solar atomosphere of which sticks out from the chromosphere to the corona. It is well found at the edge of super granules. Its diameter is about 1000km and its hight is 5000-10000 km. Mostly observed in Hydrogen alpha line. Each spicule is moving continuously, some moves upward (up rising speed is about 20 km/s) from upper chromosphere and then changes to desent, and the others are fade away after acension. Anyhow its time span is about 5 minutes.
The reason why the spicule is formed is not well known. One of well accepted models is that it is formed by the transmission of sound or magneto hydrodynamic (MHD) wave along with the strong magnetic tube swept toward the edge of granule. When the wave transmits from the photosphere to the upper chromosphere, the density decreases rapidly. Therefore the velosity disturbance in the sound and/ or MHD wave becomes larger (sometimes the shock is formed), it becomes possible to lift the upper chromosphere up to the corona.
Here we will simulate a magnetic tube with fixed foot points with perturbation on the foot points and follow its evolution as the perturbation grows and lifts the upper chromosphere to the corona.

Simulation Results


To show initial state, please place the mouse on figures.

Initially there are two layers; high density chromosphere and high temperature corona. By the Alfven wave originated in the chromosphere, the surface of the chromosphere will be lifted.

Basic Equations

Spherically symmetric Magneto Hydrodynamic equations

Detailed Explanation

Please refer THIS document (PDF file in Japanese) for detailed explanation.