Numerical simulations of fast and slow coronal mass ejections

By Tibor Török, B. Kliem. 2007

164 citations recorded by the source corpus.

Solar coronal mass ejections (CMEs) show a large variety in their kinematic properties. CMEs originating in active regions and accompanied by strong flares are usually faster and accelerated more impulsively than CMEs associated with filament eruptions outside active regions and weak flares. It has been proposed more than two decades ago that there are two separate types of CMEs, fast (impulsive) CMEs and slow (gradual) CMEs. However, this concept may not be valid, since the large data sets acquired in recent years do not show two distinct peaks in the CME velocity distribution and reveal that both fast and slow CMEs can be accompanied by both weak and strong flares. We present numerical simulations which confirm our earlier analytical result that a flux-rope CME model permits describing fast and slow CMEs in a unified manner. We consider a force-free coronal magnetic flux rope embedded in the potential field of model bipolar and quadrupolar active regions. The eruption is driven by the torus instability which occurs if the field overlying the flux rope decreases sufficiently rapidly with height. The acceleration profile depends on the steepness of this field decrease, corresponding to fast CMEs for rapid decrease, as is typical of active regions, and to slow CMEs for gentle decrease, as is typical of the quiet Sun. Complex (quadrupolar) active regions lead to the fastest CMEs. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/c5e40b9eaf1928098033d44fdadd73003fbbbfae

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Citations in the corpus

CRITERIA FOR FLUX ROPE ERUPTION: NON-EQUILIBRIUM VERSUS TORUS INSTABILITY (2010, background): “The two last phases are the most spectacular ones, so they are better constrained by observations and they are more deeply modeled, in particular with MHD simulations (e.g. Amari et al. 2003; Fan & Gibson 2007; Török & Kliem 2007).”
A MODEL FOR MAGNETICALLY COUPLED SYMPATHETIC ERUPTIONS (2011, background): “The slow rise lasts until the rope reaches the critical height for TI onset at t ≈ 40 τa, after which it rapidly accelerates upward driven by the instability (Török & Kliem 2007; Fan & Gibson 2007; Schrijver et al. 2008; Aulanier et al. 2010).”
Solar filament eruptions and their physical role in triggering Coronal Mass Ejections (2012, background): “…by the computation of a decay index, which represents the potential magnetic field drop-off along the vertical direction (zaxis): n = −d lnB/d ln z Török and Kliem (2007) found that the decay of the background magnetic field with height is a critical factor in determining whether the…”
Driving major solar flares and eruptions: A review (2008, background): “Török and Kliem (2007) discuss a unifying approach to slow and fast CMEs in which the torus instability drives the CME, and in which the gradient in the surrounding field determines the acceleration profile and eventual velocity of the ejecta: fast CMEs for rapid decrease (as typical of ARs) and…”
Nonlinear Force-free Field Modeling of a Solar Active Region around the Time of a Major Flare and Coronal Mass Ejection (2007, background): “Another is for ‘‘circuit’’ flux ropes that are produced by (thick or thin) net currents along their axes surrounded by field lines that spiral about the current (e.g., Titov & Démoulin 1999; Török & Kliem 2007).”