Time evolution of MHD disturbances impulsively excited by a localized perturber in a potential coronal arcade.
Abstract
An analytical approach to the initial value problem of MHD wave excitation in the solar corona is presented. We use the combined Fourier and Laplace transformations to solve the two-dimensional initial value problem of linear wave excitation. By this procedure, we have been able to obtain the solution for the time dependent two dimensional perturbation velocity field above the solar photosphere. Due to the physical properties of the corona, the low beta approximation has been applied to the considered processes. The perturber is initially located at a given surface in a particularly chosen frame of reference. Depending on the shape of the coronal potential magnetic arcade, this surface can be the photosphere itself, a magnetic field surface, or any other inside a magnetic arcade in hydrostatic equilibrium with the surrounding plasma. The considered excited perturbations are the fast magneto-acoustic waves which cause fluid motions, in the normal direction to the magnetic field, in the cross sectional plane of the arcade. We present an example of a given perturber located at the photosphere, showing the induced velocity field time evolution.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- April 1995
- Bibcode:
- 1995A&A...296..550C
- Keywords:
-
- MHD;
- SUN: CORONA;
- SUN: MAGNETIC FIELDS