3D Simulations of Large-Scale 3D Simulations of Large-Scale Coronal DynamicsCoronal Dynamics

Judy KarpenJudy KarpenSpiro Antiochos, Rick DeVore, Peter Spiro Antiochos, Rick DeVore, Peter MacNeice, Jim Klimchuk, Ben Lynch, MacNeice, Jim Klimchuk, Ben Lynch,

Guillaume Aulanier, Jimin GaoGuillaume Aulanier, Jimin Gao

Naval Research LaboratoryNaval Research Laboratory

http://solartheory.nrl.navy.mil/http://solartheory.nrl.navy.mil/judy.karpen@nrl.navy.miljudy.karpen@nrl.navy.mil

• What is a filament channel (FC)?What is a filament channel (FC)?

• Why are filament channels important?Why are filament channels important?

• ModelsModels

FC magnetic structure (sheared arcade)FC magnetic structure (sheared arcade)

FC plasma structure (thermal nonequilibrium)FC plasma structure (thermal nonequilibrium)

CME/flare initiation (breakout)CME/flare initiation (breakout)

• What will Solar B teach us about filament What will Solar B teach us about filament channels and CME initiation?channels and CME initiation?

What is a Filament Channel?What is a Filament Channel?

• Around neutral line (NL)Around neutral line (NL)• Core B ~// NLCore B ~// NL• Overlying B Overlying B NLNL• Exists before, after, and Exists before, after, and

without visible filamentwithout visible filament• Often persists through Often persists through

many eruptionsmany eruptions• Origin uncertainOrigin uncertain

(from Aulanier & Schmieder 2002)(from Aulanier & Schmieder 2002)

(from Deng et al. 2002)(from Deng et al. 2002)

Why are filament channels important?Why are filament channels important?

• Development is an integral Development is an integral part of the Sun’s magnetic-part of the Sun’s magnetic-field evolutionfield evolution

• Energy source and driver Energy source and driver of CMEs/eruptive flaresof CMEs/eruptive flares

• Insight into physics of Insight into physics of magnetic stability and magnetic stability and condensation processes condensation processes in cosmic and laboratory in cosmic and laboratory plasmasplasmas

Sheared Arcade Model Sheared Arcade Model

• Hypothesis:Hypothesis: observed magnetic structure is a observed magnetic structure is a natural consequence of magnetic shear (B ~// NL) natural consequence of magnetic shear (B ~// NL) in a 3D topologyin a 3D topology

• Initial conditionsInitial conditions

single bipolesingle bipole

two bipoles along same NL with different orientationstwo bipoles along same NL with different orientations

• Tests:Tests: calculations with 3D MHD fixed-grid code calculations with 3D MHD fixed-grid code

References (all ApJ):References (all ApJ): Antiochos & Klimchuk 1994; DeVore & Antiochos Antiochos & Klimchuk 1994; DeVore & Antiochos 2000; DeVore et al. 2005; Aulanier et al. 2002, 2005 (submitted)2000; DeVore et al. 2005; Aulanier et al. 2002, 2005 (submitted)

Sheared Arcade Model: ResultsSheared Arcade Model: Results

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• Bipolar (one NL) initial magnetic field Bipolar (one NL) initial magnetic field • Footpoint motion generates magnetic shear Footpoint motion generates magnetic shear • Long FC field develops as shear increasesLong FC field develops as shear increases• Stable despite significant expansion and reconnectionStable despite significant expansion and reconnection

Prominence Linkage SimulationProminence Linkage Simulation

+-

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What have we learned about FC What have we learned about FC magnetic structure?magnetic structure?

• Modest/large shear driving an Modest/large shear driving an isolated bipoleisolated bipole produces produces Sigmoids (S-shaped field associated with eruptions)Sigmoids (S-shaped field associated with eruptions)

General shape (prominence barbs and spine)General shape (prominence barbs and spine)

Mix of dipped and helical, inverse- and normal-polarity fieldsMix of dipped and helical, inverse- and normal-polarity fields

Skewed overlying arcade (as seen in EUV/SXR images)Skewed overlying arcade (as seen in EUV/SXR images)

• Modest shear driving Modest shear driving two bipolestwo bipoles produces produces Formation of large filaments by linkage of smaller onesFormation of large filaments by linkage of smaller ones

Dependence on chirality, relative axial-field orientationDependence on chirality, relative axial-field orientation

Increased complexity and helicity accumulation due to reconnectionIncreased complexity and helicity accumulation due to reconnection

Stability --- sheared bipoles do not eruptStability --- sheared bipoles do not erupt

Objectives for Solar BObjectives for Solar B

• Determine origin of magnetic shear: preexisting Determine origin of magnetic shear: preexisting flux rope or real-time photospheric motionsflux rope or real-time photospheric motions

• Observe and quantify filament growth through Observe and quantify filament growth through interacting segmentsinteracting segments Detect reconnection signaturesDetect reconnection signatures

• Reconcile multiwavelength views of FCsReconcile multiwavelength views of FCs

• Establish relationship between barbs and main Establish relationship between barbs and main structurestructure

• Investigate the role of flux emergence and Investigate the role of flux emergence and cancellation in FC formation and destabilizationcancellation in FC formation and destabilization Trace photosphere-corona couplingTrace photosphere-corona coupling

Threads: length ~ 25 Mm, width ~ 200 km Threads: length ~ 25 Mm, width ~ 200 km (SVST, courtesy of Y. Lin)(SVST, courtesy of Y. Lin)

10 Mm10 Mm

•not enough plasma in coronal flux tubes not enough plasma in coronal flux tubes mass mass must come from chromospheremust come from chromosphere

•plasma is NOT static plasma is NOT static model must be dynamicmodel must be dynamic

Plasma StructurePlasma Structure

Thermal Nonequilibrium ModelThermal Nonequilibrium Model

• Hypothesis:Hypothesis: condensations are caused by condensations are caused by heating localized above footpoints of long, heating localized above footpoints of long, low-lying loops, with heating scale << Llow-lying loops, with heating scale << L

• AssumptionsAssumptions Magnetic flux tube is rigid (low coronal Magnetic flux tube is rigid (low coronal ))

Chromosphere is mass source (evaporation) Chromosphere is mass source (evaporation) and sinkand sink

Energetics determined by heating, thermal Energetics determined by heating, thermal conduction, radiation, and enthalpy (flows)conduction, radiation, and enthalpy (flows)

References (all ApJ):References (all ApJ): Antiochos & Klimchuk 1991; Dahlburg et al. Antiochos & Klimchuk 1991; Dahlburg et al. 1998; Antiochos et al. 1999, 2000; Karpen et al. 2001, 2003; 1998; Antiochos et al. 1999, 2000; Karpen et al. 2001, 2003; Karpen et al. 2005, 2006 (in press)Karpen et al. 2005, 2006 (in press)

Why do condensations form?Why do condensations form?

• chromospheric evaporationchromospheric evaporation increases density increases density throughout corona throughout corona increased radiationincreased radiation

• T is highestT is highest within distance ~ within distance ~ from site of from site of maximum energy deposition (maximum energy deposition ( i.e.,i.e., near basenear base))

• when L > 8 when L > 8 , conduction + local heating , conduction + local heating cannot balance radiation cannot balance radiation

• rapid cooling rapid cooling local pressure deficit, local pressure deficit, pullingpulling more plasma into the condensationmore plasma into the condensation

• a a new chromospherenew chromosphere is formed where flows is formed where flows meet, reducing radiative lossesmeet, reducing radiative losses

Simulations of TN in Simulations of TN in sheared-arcade flux tubesheared-arcade flux tube

• ARGOS (ARGOS (AAdaptively daptively RRefined efined GOGOdunov dunov SSolver)olver) solves 1D solves 1D hydro equations withhydro equations with

adaptive mesh refinement adaptive mesh refinement (AMR) -- (AMR) -- REQUIREDREQUIRED

MUSCL+Godunov finite-MUSCL+Godunov finite-difference schemedifference scheme

conduction, solar gravity, conduction, solar gravity, optically thin radiationoptically thin radiation

spatially and/or temporally spatially and/or temporally variable heatingvariable heating

long dipped long dipped looploop

Note: Only quantitative, dynamic model for prominence plasmaNote: Only quantitative, dynamic model for prominence plasma

Thermal Nonequilibrium: T MovieThermal Nonequilibrium: T Movie

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NRK runNRK run

Thermal Nonequilibrium: CDS MovieThermal Nonequilibrium: CDS Movie

NRK runNRK run

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Origin of prominence massOrigin of prominence mass

• Are dips necessary?Are dips necessary? NO! NO! even loops with peak heights ≈ gravitational scale height even loops with peak heights ≈ gravitational scale height

(~50-100 Mm) form dynamic condensations(~50-100 Mm) form dynamic condensations

Flatter field lines develop longer, more massive threads and Flatter field lines develop longer, more massive threads and pairs that merge at high speeds (fastpairs that merge at high speeds (fast EUV/UV features)EUV/UV features)

• Are highly twisted flux ropes consistent with Are highly twisted flux ropes consistent with dynamics?dynamics? NO! NO! in dips deeper than f•Hg, where f measures the heating in dips deeper than f•Hg, where f measures the heating

imbalance and Hg is the gravitational scale height, knots fall imbalance and Hg is the gravitational scale height, knots fall to lowest point and stay there (grow as long as heating is on)to lowest point and stay there (grow as long as heating is on)

• Does this process still work for a field line from Does this process still work for a field line from the sheared-arcade model? the sheared-arcade model? YES!YES!

• With episodic heating? With episodic heating? YES!YES! if not too impulsive…if not too impulsive…

What have we learned about What have we learned about FC plasma structure?FC plasma structure?

red = too shortred = too shortgreen = too tallgreen = too tall

black = too deepblack = too deepblue = just rightblue = just right

Note: Distribution of field line shapes (area & height variations) Note: Distribution of field line shapes (area & height variations) dictates distribution of stationary/dynamic plasma dictates distribution of stationary/dynamic plasma for any modelfor any model

Objectives for Solar BObjectives for Solar B

• Determine how prominence mass is brought up Determine how prominence mass is brought up from the chromosphere: jets, levitation, or from the chromosphere: jets, levitation, or evaporation evaporation

• Coincident multiwavelength observations of Coincident multiwavelength observations of condensation formation and evolutioncondensation formation and evolution Reconcile HReconcile H and EUV measurements of plasma motions and EUV measurements of plasma motions

• Deduce spatial and temporal characteristics of Deduce spatial and temporal characteristics of coronal heating in filament channelcoronal heating in filament channel

CME/eruptive flare initiationCME/eruptive flare initiation

• Eruption requires thatEruption requires that

Energy is stored in the Energy is stored in the coronal magnetic fieldcoronal magnetic field

FC is the only place where FC is the only place where the field is sufficiently the field is sufficiently nonpotential to contain this nonpotential to contain this energyenergy

Overlying field must be Overlying field must be removedremoved

Hypothesis:Hypothesis: multipolar field provides a natural multipolar field provides a natural mechanism for meeting these requirements mechanism for meeting these requirements

2.5D Breakout Model2.5D Breakout Model

• MHD simulations with ARMS (adaptive mesh, massively //)MHD simulations with ARMS (adaptive mesh, massively //)

• Add 2D (axisymmetric) “AR” dipole to global dipoleAdd 2D (axisymmetric) “AR” dipole to global dipole

• Global evolution controlled by small-scale diffusion regionGlobal evolution controlled by small-scale diffusion region

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References (ApJ except as noted):References (ApJ except as noted): Antiochos 1998;Antiochos 1998; Antiochos et al. 1999; Lynch et al. 2004; Antiochos et al. 1999; Lynch et al. 2004; MacNeice et al. 2004; Phillips et al. 2005; Gao 2005 and Lynch 2005 (PhD theses, in preparation)MacNeice et al. 2004; Phillips et al. 2005; Gao 2005 and Lynch 2005 (PhD theses, in preparation)

• Eruption similar to axisymmetric case, but all field lines remain connected to Eruption similar to axisymmetric case, but all field lines remain connected to photospherephotosphere

• V > 1000 km/s V > 1000 km/s

• Simulation with outer boundary at 30 RSimulation with outer boundary at 30 Rsunsun in progress in progress

3D Asymmetric Breakout Model3D Asymmetric Breakout Model

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Breakout Flare Ribbons Breakout Flare Ribbons (2D)(2D)

• Ribbons appear after eruption on Ribbons appear after eruption on either side of a neutral lineeither side of a neutral line

• Breakout model reproduces generic Breakout model reproduces generic current-sheet flare-loop geometrycurrent-sheet flare-loop geometry

• Loops grow in height and Loops grow in height and footpoints separate with timefootpoints separate with time

(from Fletcher et al.)

Roles of ReconnectionRoles of Reconnection

• Initial breakout reconnectionInitial breakout reconnection Removes overlying flux by transfer to adjacent systemRemoves overlying flux by transfer to adjacent system

Feedback loop between plasmoid acceleration and Feedback loop between plasmoid acceleration and reconnection ratereconnection rate

• Two phases of flare reconnectionTwo phases of flare reconnection Initial (impulsive?) reconnection in low-Initial (impulsive?) reconnection in low-, strong guide-, strong guide-

field region (sheared): shocks, particle acceleration, field region (sheared): shocks, particle acceleration, HXR/HXR/wave burstswave bursts

Main phase (gradual?) reconnection in neutral sheet Main phase (gradual?) reconnection in neutral sheet below prominence (unsheared flux): magnetic islands, below prominence (unsheared flux): magnetic islands, flare ribbons, and “post-flare” EUV/SXR loopsflare ribbons, and “post-flare” EUV/SXR loops

What have we learned What have we learned about FC eruption?about FC eruption?

• Energy for CMEs stored in sheared 3D field held Energy for CMEs stored in sheared 3D field held down by overlying unsheared fielddown by overlying unsheared field

• Breakout model yields unified explanation forBreakout model yields unified explanation for

pre-eruption prominence structurepre-eruption prominence structure fast eruption (reconnection rate grows fast eruption (reconnection rate grows

exponentially)exponentially) magnetic energy above that of the open statemagnetic energy above that of the open state ““post-flare” loopspost-flare” loops flux ropes in heliosphereflux ropes in heliosphere

• Flux ropes are Flux ropes are formedformed by flare reconnection by flare reconnection

Objectives for Solar BObjectives for Solar B

• Search for signatures of breakout reconnection: Search for signatures of breakout reconnection: jets, crinkles, energetic particles, etc.jets, crinkles, energetic particles, etc.

• Establish temporal and spatial relationships Establish temporal and spatial relationships among eruption features (among eruption features (e.g.,e.g., reconnection reconnection signatures, EUV dimmings, flare ribbons)signatures, EUV dimmings, flare ribbons)

• Determine whether flux rope forms before or Determine whether flux rope forms before or after eruptionafter eruption

• Test correlation between flare phase and Test correlation between flare phase and amount of shear on reconnecting fluxamount of shear on reconnecting flux

SummarySummary

• Sheared arcade model:Sheared arcade model: filament magnetic filament magnetic structure is produced bystructure is produced by strong shear (NOT strong shear (NOT twist) near and parallel to neutral linetwist) near and parallel to neutral line

• Thermal nonequilibrium model:Thermal nonequilibrium model: dynamic and dynamic and static condensations are produced by normal static condensations are produced by normal coronal heating localized at base of loopscoronal heating localized at base of loops

• Breakout model:Breakout model: eruptions are produced by eruptions are produced by shearing of filament channel (inner core) within shearing of filament channel (inner core) within multipolarmultipolar topologies topologies

• Progressing toward a complete, self-consistent, Progressing toward a complete, self-consistent, 3D model of filament-channel lifecycle3D model of filament-channel lifecycle

Our Goals for Solar BOur Goals for Solar B

• Reveal origin and evolution of magnetic Reveal origin and evolution of magnetic structure of filament channels structure of filament channels Test sheared arcade modelTest sheared arcade model

• Determine primary source of filament massDetermine primary source of filament mass Test thermal nonequilibrium modelTest thermal nonequilibrium model

• Establish the roles of multipolarity and Establish the roles of multipolarity and reconnection in CME+flare initiation/ reconnection in CME+flare initiation/ evolutionevolution Test magnetic breakout modelTest magnetic breakout model