The Relationship Between CMEs and Post-

eruption Arcades

The Relationship Between CMEs and Post-

eruption ArcadesPeter T. Gallagher, Chia-Hsien

Lin, Claire Raftery, Ryan O. Milligan

Peter T. Gallagher, Chia-Hsien Lin, Claire Raftery, Ryan O.

Milligan

Recap of CME MorphologyRecap of CME Morphology

“Typical” event consists of 3 components:Ejection of coronal magnetic field and massEjection of filament/prominence field and

massHeating of > 10MK flare coronal loops and

acceleration of flare particles (Krucker) Strength of each component can vary

between events, but all are present to some degreeHow are they related?

“Typical” event consists of 3 components:Ejection of coronal magnetic field and massEjection of filament/prominence field and

massHeating of > 10MK flare coronal loops and

acceleration of flare particles (Krucker) Strength of each component can vary

between events, but all are present to some degreeHow are they related?

Non-Dipole Coronal TopologyNon-Dipole Coronal Topology

Field of two dipoles – axi-symmetricLarge global at Sun center, weaker near

surfaceMust have 4-flux system with separatrix

bdys, and null

Field of two dipoles – axi-symmetricLarge global at Sun center, weaker near

surfaceMust have 4-flux system with separatrix

bdys, and null

Non-eruptionNon-eruption• Bipolar (one polarity inversion line) initial magnetic field • Filament-field formation by shearing and reconnection• See pronounced expansion & kinking – but no eruption

Underlying physics: Corona has no lid Magnetic field lines can stretch indefinitely

without breakingFree to open slowly in response to photospheric

stress and gas pressure (rather than erupt as CME) Slow opening (not associated with filament

channels) observed to occur continuously in large-scale corona

• Bipolar (one polarity inversion line) initial magnetic field • Filament-field formation by shearing and reconnection• See pronounced expansion & kinking – but no eruption

Underlying physics: Corona has no lid Magnetic field lines can stretch indefinitely

without breakingFree to open slowly in response to photospheric

stress and gas pressure (rather than erupt as CME) Slow opening (not associated with filament

channels) observed to occur continuously in large-scale corona

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(from, DeVore et al, 2005; Aulanier et al, 2005)

Breakout ModelBreakout Model

2D multi-polar initially potential field Create filament channel by simple footpoint

motions Outward expansion drives breakout

reconnection in corona

2D multi-polar initially potential field Create filament channel by simple footpoint

motions Outward expansion drives breakout

reconnection in corona

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Breakout ModelBreakout Model

Breakout reconnection allows for explosive eruption

Flare current sheet, flare reconnection, and twisted flux rope all consequences of ejection

CME with no flare possible for slow eruptions

Breakout reconnection allows for explosive eruption

Flare current sheet, flare reconnection, and twisted flux rope all consequences of ejection

CME with no flare possible for slow eruptions

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Ideal InstabilityIdeal Instability

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Open CME questionsOpen CME questions

What are the forces governing the propagation and expansion of CMEs?

Is there a relationship between CME kinematics and post-flare loop kinematics?

What are the forces governing the propagation and expansion of CMEs?

Is there a relationship between CME kinematics and post-flare loop kinematics?

CME KinematicsCME Kinematics

Kinematics are governed by force balance equation:

Kinematics are governed by force balance equation:

€

ρ D ˆ v

Dt= −∇P + ˆ J × ˆ B −

GMρ

R2ˆ R

€

ˆ J =c

4π∇ × ˆ B

Standard Flare ModelStandard Flare Model

CME ModelsCME Models

• All models are based on the principle that CMEs are driven by the sudden release of the free magnetic energy stored in pre-eruptive coronal magnetic fields.

– Resistive MHD models: where magnetic reconnection in a current sheet plays an important role in triggering the CME onset and in sustaining the eruption.

– Ideal resistive hybrid: where eruption is triggered by an ideal loss of equilibrium of the magnetic field but that subsequent formation of a current sheet and magnetic reconnection is crucial for sustaining the eruption and allowing a magnetic flux rope to escape.

– Non-force free models: the weight of the prominence mass plays a important role in building up the magnetic energy to exceed that of the open-field limit, and that a sudden drop of the prominence weight triggers the eruption.

• All models are based on the principle that CMEs are driven by the sudden release of the free magnetic energy stored in pre-eruptive coronal magnetic fields.

– Resistive MHD models: where magnetic reconnection in a current sheet plays an important role in triggering the CME onset and in sustaining the eruption.

– Ideal resistive hybrid: where eruption is triggered by an ideal loss of equilibrium of the magnetic field but that subsequent formation of a current sheet and magnetic reconnection is crucial for sustaining the eruption and allowing a magnetic flux rope to escape.

– Non-force free models: the weight of the prominence mass plays a important role in building up the magnetic energy to exceed that of the open-field limit, and that a sudden drop of the prominence weight triggers the eruption.

Overview of 17-Dec-2006 Event

Overview of 17-Dec-2006 Event

CME KinematicsCME Kinematics

Post-flare arcade kinematics

Post-flare arcade kinematics

CME and Arcade Kinematics

CME and Arcade Kinematics

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24-hours

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Comparison of eventsComparison of events

21-apr-2002

17-Dec-2006

vmax

(km/s)

~2,4001-10

~790~1

amax

(m/s/s)

Duration(hours)

~20 ~13

X-ray magnitud

e

X1.1 C2.0

A comparable event: 21-Apr-2002

A comparable event: 21-Apr-2002

ConclusionsConclusions

Is there a relationshipIs there a relationship

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