On the dynamics and structure of coronal mass ejections

Abstract

This paper investigates a number of general properties of loop-shaped coronal mass ejections (CMEs). It is shown that at distances 2.5 R⊙ ⩽ R ⩽ 10 R⊙ from the Sun's center the motion of CME in the plane of sky can be visualized as the radial motion of a quasi-circular region in the antisunward direction with the velocity of the center of gravity ≈ ( V p − V ⊥) and a simultaneous expansion with respect to this center with velocity V ⊥, with the quasi-circular shape remaining unchanged. At a certain distance r > 2.5 R⊙ the relationship V ⊥ V gr − V ⊥≈ const begins to be saturated. Using an improved variant of Webb's (1988) ( J. geophys. Res. 93, 1749) model it is shown that, according to its structure, the CME can be shaped both as a loop and as a shell and as a filled shell. With the obtained properties allowed for, we have calculated the velocity V r of the CME's forefront, its mass and total kinetic energy E for cases where the motion of the CME occurs at an angle β to the plane of sky.