A Twisted Flux Rope Model for Coronal Mass Ejections and Two-Ribbon Flares

Abstract

We present a new approach to the theory of large-scale solar eruptive phenomena such as coronal mass ejections and two-ribbon flares, in which twisted flux tubes play a crucial role. We show that it is possible to create a highly nonlinear three-dimensional force-free configuration consisting of a twisted magnetic flux rope representing the magnetic structure of a prominence (surrounded by an overlaying, almost potential, arcade) and exhibiting an S-shaped structure, as observed in soft X-ray sigmoid structures. We also show that this magnetic configuration cannot stay in equilibrium and that a considerable amount of magnetic energy is released during its disruption. Unlike most previous models, the amount of magnetic energy stored in the configuration prior to its disruption is so large that it may become comparable to the energy of the open field.

Solar Weather Event Modelling and Prediction

“…Tethers are the field lines that provide the tension in analogy to ropes that hold down a buoyant balloon. Emergence or cancellation of magnetic flux could lead to break-off of the tethers as proposed by several authors (e.g., Mikić and Linker 1999; Amari et al 2000) and matching the observational photospheric magnetic field characteristics of the CME source region events studied by Bothmer and Tripathi (2007). In the tether straining model the strain on the tethers is gradually increased until they brake as introduced in the breakout models by Antiochos (1998) or Linker and Mikić (1995).…”

“…Simulations by Krall et al (2000) use injection of magnetic flux as driving mechanism in which pre-existing fields become twisted, new ring-shaped field lines rise upward in the corona while becoming detached from the photosphere and new arch-shaped field lines emerge into the corona while staying anchored at their photospheric footpoints. Chen (1996) and Roussev et al (2004) amongst others assume a priori that the structure of a CME is that of a magnetic flux rope in agreement with the findings by on the 3-D structure of CMEs derived from SOHO/LASCO Dryer et al (1979) , Wu (1982 Dynamo Model Instabilities of sheared and twisted coronal loops Photospheric footpoint motions, emerging flux; kink-instability Klimchuk (1990), Török et al (2003), Blackman and Brandenburg (2003) Mass Loading Model Slow build-up of magnetic stress and subsequent instability: magnetic buoyancy Mass loading through evolving prominence/filament; plasma instabilities in coronal streamers Low (1996), Hundhausen (1999), Gibson and Low (2000), Low (2003), Manchester et al (2004) Tether Release Model Magnetic pressure imbalance of coronal loops Localized instabilities of coronal loops due to reconnection processes initiating a catastrophic explosion on larger-scale Forbes and Priest (1995), Titov and Démoulin (1999), Mikić and Linker (1999), Amari et al (2000), Roussev et al (2003) Tether Straining Model Increase of the strain of coronal loops and breakout Reconnection of sheared multipolar magnetic field configurations Antiochos (1998), ...…”

Merging of coronal and heliospheric numerical two‐dimensional MHD models

“…The shearing phase is not intended to model actual flows on the Sun; it is just a convenient mechanism for producing strongly sheared field lines that are nearly aligned with the neutral line [Amari et al, 2000;Linker et al, 2001]. The shearing phase lasts 5.2 days, during which a flow of <2 Figure 2.…”

From the Sun’s atmosphere to the Earth’s atmosphere: an overview of scientific models available for space weather developments

“…(Amari et al, 2000) (semi) and implicit Strasbourg (France) cylindrical coronal MHD (Baty and Heyvaerts, 1996) Boundary conditions stability Pisa / Firenze (Italy) cylindrical (3D) San Diego coronal MHD (Lionello et al, 1998) 2D reduced MHD turbulence Nice (France) 1D, 2D Turbulence (Galtier et al, 1997) Finite differences, Spectral Intermittence Argentina Reduced MHD (2D+) Turbulence (Dmitruk et al, 1998) Cartesian Flare-heating Spectral (Fourrier) University of Michigan (USA) 2D, 2.5D, 3D (?) Comets -wind (Israelevich et al, 2001) Roe scheme astrophysics Finite volumes NCSA (Illinois) 2.5D, (3D ?)…”