Disruption of a Helmet Streamer by Photospheric Shear
Abstract
Helmet streamers on the Sun have been observed to be the site of coronal mass ejections, dynamic events that eject coronal plasma and magnetic fields into the solar wind. We develop a two-dimensional (azimuthally symmetric) helmet streamer configuration by computing solutions of the time-dependent magnetohydrodynamic (MHD) equations, and we investigate the evolution of the configuration when photospheric shearing motions are imposed. We find that the configuration disrupts when a critical shear is exceeded, ejecting a plasmoid into the solar wind. The results are similar to the case of a sheared dipole magnetic field in a hydrostatic atmosphere (Mikic & Linker 1994). However, the presence of the outflowing solar wind makes the disruption significantly more energetic when a helmet streamer is sheared. Our resutls suggest that shearing of helmet streamers may initiate coronal mass ejections.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- January 1995
- DOI:
- 10.1086/187711
- Bibcode:
- 1995ApJ...438L..45L
- Keywords:
-
- Astronomical Models;
- Mathematical Models;
- Photosphere;
- Shearing;
- Solar Corona;
- Solar Magnetic Field;
- Solar Wind;
- Stellar Mass Ejection;
- Coronagraphs;
- Magnetohydrodynamics;
- Plasma Dynamics;
- Plasmas (Physics);
- Solar Physics;
- SUN: CORONA;
- SUN: MAGNETIC FIELDS;
- SUN: SOLAR WIND