Coronal mass ejections as expanding force-free structures

Abstract

We mode Solar coronal mass ejections (CMEs) as expanding force-fee magnetic structures and find the self-similar dynamics of configurations with spatially constant α, where {\bf J} =α{\bf B}, in spherical and cylindrical geometries, expanding spheromaks and expanding Lundquist fields correspondingly. The field structures remain force-free, under the conventional non-relativistic assumption that the dynamical effects of the inductive electric fields can be neglected. While keeping the internal magnetic field structure of the stationary solutions, expansion leads to complicated internal velocities and rotation, induced by inductive electric field. The structures depends only on overall radius R(t) and rate of expansion \dot{R}(t) measured at a given moment, and thus are applicable to arbitrary expansion laws. In case of cylindrical Lundquist fields, the flux conservation requires that both axial and radial expansion proceed with equal rates. In accordance with observations, the model predicts that the maximum magnetic field is reached before the spacecraft reaches the geometric center of a CME.

19 pages, 9 Figures, accepted by Solar Physics

References in corpus (3)

• Fields from a relativistic magnetic explosion
• Relativistic expansion of a magnetized fluid
• Investigation of Dynamics of Self-Similarly Evolving Magnetic Clouds

Cited by in corpus (7)

• Plasma Heating During a Coronal Mass Ejection Observed by SOHO
• Magnetic field structure of relativistic jets without current sheets
• Magnetic loading of magnetars' flares
• Relativistic magnetic explosions
• Dynamics of rising magnetized cavities and UHECR acceleration in clusters of galaxies
• Tilting Instability of Magnetically Confined Spheromaks
• Radio afterglow of magnetars' giant flares