ON THE SPONTANEOUS FORMATION OF ELECTRIC-CURRENT SHEETS ABOVE A FLEXIBLE SOLAR PHOTOSPHERE

被引:23
作者
LOW, BC
机构
[1] High Altitude Observatory, Natl. Ctr. for Atmospheric Research, Boulder, CO 80307
关键词
HYDROMAGNETICS; SUN; CORONA; MAGNETIC FIELDS;
D O I
10.1086/170651
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
This paper treats the general tendency for a magnetic field in an electrically perfectly conducting plasma to seek an equilibrium state with embedded electric current sheets or magnetic tangential discontinuities, a hydromagnetic property first pointed out by Parker. This property is simplest to demonstrate theoretically with two-dimensional force-free magnetic fields in the infinite half-space above a plane boundary where magnetic footpoints are rigidly anchored. The principal results of recent treatments of this simple model are summarized and extended to clarify their basic physics in order to answer the criticism of this model by Karpen, Antiochos, & DeVores in 1990. Based on a numerical simulation and a certain (incorrect) interpretation of the forces associated with an electric current sheet, these authors have concluded that the formation of current in this model depended on the use of rigid boundary conditions to the extent that current sheets would not form if the boundary is not rigid but is replaced by a gravitationally stratified photosphere of finite thickness. It is shown that the conclusion of these authors is not valid, based on a physical analysis and an explicit magnetostatic construction of a possible equilibrium state in which a current sheet has formed in the presence of a flexible photosphere. Some suggestions for future numerical studies are given.
引用
收藏
页码:295 / 305
页数:11
相关论文
共 37 条
[1]  
ALY JJ, 1989, A A, V221, P289
[2]  
ALY JJ, 1987, P WORKSHOP INTERSTEL, P240
[3]  
AMARI T, 1990, ADV SOLAR SYSTEM MAG, P3
[4]   THE TOPOLOGY OF FORCE-FREE MAGNETIC-FIELDS AND ITS IMPLICATIONS FOR CORONAL ACTIVITY [J].
ANTIOCHOS, SK .
ASTROPHYSICAL JOURNAL, 1987, 312 (02) :886-894
[5]  
Berger M. A., 1989, Turbulence and Nonlinear Dynamics in MHD Flows. Proceedings of the Workshop, P197
[6]  
COULSON CA, 1958, ELECTRICITY
[7]  
COURANT R, 1962, METHODS MATH PHYSICS, V2
[8]  
Field G. B., 1990, Topological Fluid Mechanics. Proceedings of the IUTAM Symposium, P244
[9]   ON THE FORMATION OF CURRENT SHEETS IN THE SOLAR CORONA [J].
KARPEN, JT ;
ANTIOCHOS, SK ;
DEVORE, CR .
ASTROPHYSICAL JOURNAL, 1990, 356 (02) :L67-L70
[10]  
KARPEN JT, 1991, IN PRESS APJ