Using MHD numerical simulations in a three-dimensional spherical geometry, we model the loss of confinement and eruption flux rope emerging quasi-statically into preexisting coronal arcade field. Our experiments investigated two distinct mechanisms that led to rope. In one case, overlying field declines with height slowly such remains confined until its self-relative magnetic helicity normalized by square rope's reaches -1.4 becomes significantly kinked. The kinking motion causes rotation...

We report the results of a three-dimensional MHD simulation dynamic emergence twisted, Ω-shaped tube from top layer solar convection zone into atmosphere and corona. It is found that segment at apex Ω-tube expands stably stratified as result magnetic buoyancy instability (or Parker instability). Our left-hand-twisted reproduces several major observed features newly developing active region described by Strous coworkers, including orientation arch-filament system, distribution vertical field...

We present a three-dimensional numerical magnetohydrodynamic simulation designed to model the emergence of magnetic flux rope passing from below photosphere into corona. For initial state, we prescribe plane-parallel atmosphere that comprises polytropic convection zone, photosphere, transition region, and Embedded in this system is an isolated horizontal located 10 photospheric pressure scale heights photosphere. The uniformly twisted, with plasma temperature inside reduced compensate for...

view Abstract Citations (304) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Origin of Morphological Asymmetries in Bipolar Active Regions Fan, Y. ; Fisher, G. H. Deluca, E. A series 3D numerical simulations was carried out to examine the dynamical evolution emerging flux loops solar convective envelope. innermost portions are anchored beneath base zone by subadiabatic temperature gradient underlying overshoot region. It is found that, as...

We present the results of MHD simulations in low-β regime evolution three-dimensional coronal magnetic field as an arched, twisted flux tube emerges into a preexisting potential arcade. find that line-tied emerging becomes kink-unstable when sufficient amount twist is transported corona. For with left-handed (which preferred sense for active region tubes northern hemisphere), kink motion and its interaction ambient lead to formation intense current layer displays inverse-S shape, consistent...

Abstract Active regions on the solar surface are generally thought to originate from a strong toroidal magnetic field generated by deep seated dynamo mechanism operating at base of convection zone. Thus fields need traverse entire zone before they reach photosphere form observed active regions. Understanding this process region flux emergence is therefore crucial component for study cycle dynamo. This article reviews studies with regard formation and rise scale tubes in their into atmosphere as

To investigate the dynamic evolution of a coronal magnetic field in response to emergence significantly twisted structures, we perform MHD simulations low-β regime flux tube into preexisting potential arcade. Our simulation tube, which when fully emerged contains twist 1.875 × 2π field-line rotation about axis between anchored footpoints, leads structure with substantial writhing (with an apex >90°) as result nonlinear kink instability. For emerging left-handed (which is preferred sense for...

view Abstract Citations (194) References (39) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Dynamics of Emerging Active Region Flux Loops Fan, Y. ; Fisher, G. H. McClymont, A. N. The buoyant rise a magnetic flux loop arising from single perturbed segment toroidal ring lying slightly beneath the base convection zone is studied by way numerical simulations. We have considered evolution assuming both solid-body rotation, and differential rotation consistent...

The solar prominence is an example of a space physics phenomenon that can be modeled as twisted magnetic flux tube or “rope.” In such models the one observable part larger structure capable storing energy to drive eruptions. We show how rope model explains range observations prominences and associated structures cavities soft X‐ray sigmoids discuss in particular observational dynamic consequences three‐dimensional reconnections around evolving rope. demonstrate describe prominence's...

We report the results of a magnetohydrodynamic (MHD) simulation convective dynamo in model solar envelope driven by radiative diffusive heat flux. The produces large-scale mean magnetic field that exhibits irregular cyclic behavior with oscillation time scales ranging from about 5 to 15 yr and undergoes polarity reversals. axisymmetric toroidal is opposite signs two hemispheres concentrated at bottom convection zone. presence fields found play an important role self-consistent maintenance...

We present three-dimensional MHD simulations of the evolution magnetic field in corona where emergence a twisted flux tube is driven at lower boundary into pre-existing coronal potential arcade field. Through sequence which we vary amount transported before stopped, investigate conditions that lead to dynamic eruption resulting rope. It found critical condition for onset center rope reach height corresponding declines with sufficiently steep rate, consistent torus instability In some cases,...

Determining the 3D coronal magnetic field is a critical, but extremely difficult problem to solve. Since different types of multiwavelength data probe aspects field, ideally these should be used together validate and constrain specifications that field. Such task requires ability create observable quantities at range wavelengths from distribution associated plasma -- i.e., perform forward calculations. In this paper we describe capabilities FORWARD SolarSoft IDL package, uniquely...

We perform MHD simulations in a spherical geometry of the evolution three-dimensional coronal magnetic field as twisted flux tube emerges slowly into low-β corona previously occupied by potential arcade. study emerged rope its twist and energy increases due to emergence. find two distinct stages evolution. The earlier is nearly quasi-static, with being able settle an neighboring equilibrium when emergence stopped. When reaches some critical level, found undergo kink motion erupt through...

The anelastic approximation has strong advantages for numerical simulations of stellar and solar convection zones. chief generally known one is that it suppresses acoustic modes, permitting larger simulated time steps to be taken than would possible in a fully compressible model. This paper clarifies extends previous work on the by presenting new vorticity-based formulation can used two- three-dimensional MHD simulations. In formulation, all fluctuating thermodynamic variables except entropy...

We demonstrate the partial expulsion of a three-dimensional magnetic flux rope, in which an upper, escaping rope is separated from lower, surviving by cusped, reconnecting loop field lines. use magnetohydrodynamic model recently presented Fan, extended to examine erupting rope's end state. As that work, modeled spherical coordinates erupts when enough twist has emerged induce loss equilibrium. After multiple reconnections at current sheets form during eruption, breaks two, so only part it...

Recent studies of the dynamic evolution magnetic flux tubes in solar convection zone are reviewed with focus on emerging responsible for formation active regions. The current prevailing picture is that regions surface originate from strong toroidal fields generated by dynamo mechanism at thin tachocline layer base zone. Thus need to traverse entire before they reach photosphere form observed This review discusses results regard following major topics:

We present a 3D simulation of the dynamic emergence twisted magnetic flux tube from top layer solar convection zone into atmosphere and corona. It is found that after brief initial stage during which two polarities bipolar region become separated tubes intersecting photosphere vertical, significant rotational motion sets in within each polarity. The motions are to twist up inner field lines emerged fields such they change their orientation an inverse configuration (i.e. pointing negative...

We show that a numerical simulation of magnetic flux rope emerging into coronal field predicts solar structures and dynamics consistent with observations. first consider the structure, evolution, relative location orientation -shaped, or sigmoid, active regions filaments. The basic assumptions are (1) X-ray sigmoids appear at known as "bald-patch-associated separatrix surfaces (BPSSs), where, under dynamic forcing, current sheets can form, leading to reconnection localized heating, (2)...

view Abstract Citations (157) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Morphology of Flare Phenomena, Magnetic Fields, and Electric Currents in Active Regions. I. Introduction Methods Canfield, Richard C. ; de La Beaujardiere, J. -F. Fan, Yuhong Leka, K. D. McClymont, A. N. Metcalf, Thomas R. Mickey, Donald L. Wuelser, Jean-Pierre Lites, Bruce W. current systems solar active regions their spatial relationship to sites electron...

We present a set of three-dimensional spherical shell anelastic MHD simulations the buoyant rise magnetic flux tubes from base convection zone to depth 16 Mm below photosphere. It is found that when twisted tube arches upward due buoyancy, it rotates out plane and thus produces tilt at apex. Our show for with twist rate necessary cohesive rise, twist-induced dominates caused by Coriolis force, furthermore, wrong direction (opposite observational Joy's law) if left-handed (right-handed) in...

The Coronal Multi-channel Polarimeter (CoMP) obtains daily full-Sun above-the-limb coronal observations in linear polarization, allowing for the first time a diagnostic of magnetic field direction quiescent prominence cavities. We find that these cavities consistently possess characteristic "lagomorphic" signature polarization indicating twist or shear extending up into cavity above neutral line. demonstrate such may be explained by flux-rope model, topology with implications solar...

We use a thin flux tube model in rotating spherical shell of turbulent convective flows to study how active region scale tubes rise buoyantly from the bottom convection zone near solar surface. investigate toroidal at base with field strengths ranging 15 kG 100 initial latitudes 1° 40° total 1022 Mx. find that dynamic evolution changes dominated magnetic buoyancy as strength increases kG. At kG, development Ω-shaped rising loops is mainly controlled by growth instability. However, low...

We present a realistic numerical model of sunspot and active region formation based on the emergence flux bundles generated in solar convective dynamo. To this end we use magnetic velocity fields horizontal layer near top boundary dynamo simulation to drive radiative-magnetohydrodynamic simulations upper most layers convection zone. The main results are: (1) emerging rise with mean speed upflows, fragment into small-scale elements that further photosphere, where bipolar pairs are formed...

Abstract It has been a prevailing picture that active regions on the solar surface originate from strong toroidal magnetic field stored in overshoot region at base of convection zone, generated by deep seated dynamo mechanism. This article reviews studies regard to how can destabilize and rise through zone form observed surface. Furthermore, new results global simulations convective dynamos, near-surface layer formation, together with helioseismic investigations pre-emergence regions, are...