Slow Solar Wind Formation Beyond the Cusp of an Helmet Streamer
Abstract
The region beyond the cusp of an helmet streamer is characterized by the presence of a current sheet embedded in a plasma flow. In previous 3D and 2D simulations the velocity has been found, at a fixed radius, to grow from a slow value at the current sheet towards higher values towards the polar regions. The steady-state which was reached showed the bimodal characteristic of the solar wind, but the slow component did not show its characteristic variability. The velocity profile of the slow component is in fact not steady in time, and plasma density enhancements have been observed by the Large-Angle Spectrometric Coronagraph (LASCO) instrument on board the Solar and Heliospheric Observatory (SOHO). We present numerical simulations, performed with the SAIC MHD spherical code (MAS), of the region beyond the cusp of an helmet streamer from 1 R\odot up to 20 R\odot. With a sufficiently high resolution magnetic reconnection of the heliospheric current sheet is observed, which leads to the formation of density-enhanced magnetic islands that are accelerated radially outward. The reconnection process also gives rise to an acceleration profile that is not steady in time.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFMSH21A0290R
- Keywords:
-
- 7524 Magnetic fields;
- 7526 Magnetic reconnection (2723;
- 7835);
- 7839 Nonlinear phenomena (4400;
- 6944)