CME Eruption at the Sun and Ejecta Magnetic Field at 1 AU

CME Eruption at the Sun and Ejecta Magnetic Field at 1 AU

Valbona KunkelSolar Physics Division, Naval Research Laboratory

Collaborator: J. Chen

[email protected]

April 15 2013 12th Annual International Astrophysics Conference

NRL Solar Physics Division

Hundhausen (1999)

“MAGNETIC FORCES”: MAGNETIC GEOMETRY OF CMEs

3D Geometry of CMEs–3 Part Morphology

Illing and Hundhausen (1986) Chen et al (1997)SOHO

• Dominant consensus from the 1980s and1990s (SMM era): CMEs are dome-like structures with rotational symmetry, not a thin flux rope Neither of the above

SMM


INTRODUCTION: CME-FLARE PHYSICS

Key Questions in Coronal Mass Ejection (CME) Physics and New Answers:

• What forces drive CMEs?—evolution of a CME and its B field from the Sun (to 1 AU)

• What is the physical connection between CMEs and associated flares?

• What is the energy source? Open physics issues—quantified

A Physical Model of CMEs:

• The Erupting Flux Rope (EFR) model of CMEs: a quantitative theoretical model that correctly replicates observed CME dynamics—direct comparison with data:

– CME position-time data from the Sun to 1 AU (STEREO)

– in situ B(t) and plasma measurements of CME ejecta at 1 AU (STEREO, ACE)

– CME data and associated flare (GOES) X-ray (SXR) data (near-Sun processes)

Theme of This Talk:• What extractable physical information do data contain? Theory-data comparison at

both ends of the Sun-Earth region and the intervening CME trajectory.


THEORY-DATA RELATIONSHIP

Physics Models: Characteristic Physical Scales

• MHD is scale invariant—models are distinguished by characteristic scales• The EFR model---defined by MHD equations for macroscopic flux-rope dynamics

• What determines the flux-rope motion?---3D flux-rope geometry and physical scales

‒ Lorentz hoop force:

‒ A 3D plasma structure: and evolve

‒ Stationary footpoints: Sf = const and

• Initial equilibrium conditions:

B0, MT0 Acceleration time scale (Alfvenic)

• How are these scales manifested in the data?

2 2 2 2/ 0, / 0d Z dt d a dt

Sf

R

a

2 2( ) / ( ) / ( ) ln(8 / ) / 2 / /p p c pdV t dt t L t R a R a B B

2 2/ ( , , )a t pd a dt F B B p

2 2( ) / 4 / 2 ( )fR t Z S Z t

( ) ln 8 /L t R R a


Dynamical Scales

Sf -SCALING OF FLUX-ROPE ACCELERATION

Chen, Marque, Vourlidas, Krall, and Schuck (2006)

22

2 ln (8 / )f

f

Sd ZR R adt

Sf – Scaling

A geometrical effect – a flux rope at t = 0 and accelerated by the Lorentz hoop force

Directly manifested in data—3D geometrical effect/ /R Ap paR V R B


PHYSICAL INFORMATION IN DATA: Best-Fit Solutions

• Extract physical information from observations—constrain the model by only the observed height-time data, Zdata(ti), and calculate the best-fit solution, Zth(ti)

‒ Minimize the average deviation from the data (maximize the goodness of fit)

‒ data, model solution, and uncertainty at the i-th observing time

• Adjust Sf and to minimize D

‒ A “shooting” method

‒ Sf and calculated by the best-fit solution are the physical predictions of

the EFR model constrained by the height-time data

• The best-fit solutions can produce other physical predictions that can be tested

‒ Hypothesis:

1

| ( ) ( ) |1 Ndata i th i

ii

Z t Z tDT Z

( ), ( ),data i th i iZ t Z t Z

( ) /pd t dt

( ) /pd t dt

( ) (1/ ) ( ) /pemf t c d t dt ( ) ( )SXRemf t I t


INITIAL-VALUE SOLUTIONS

Input Parameters

• Model corona—specified and unchanged

‒ pc(Z), nc(Z), Bc(Z), Vsw(Z), Cd ,

• Observational constraints

‒ Sf, Zdata(ti), ISXR(t)

Model Outputs

• Initial field and mass—calculated, intrinsic

‒ Initial equilibrium conditions B0, Mt0, p0

• Initial-value solution

‒ Sf, “shooting parameter”

‒ Minimize D Sf, are physical predictions

Sf

p

Z

( ) /pd t dt

( ) /pd t dt

1.18


EMF: CME-FLARE CONNECTION

D = 1.3% Z0 = 2.5 x 105 km Sf = 4.25 x 105 km <E>max = 3.7 V/cm

X

1

| ( ) ( ) |1 Ndata i th i

ii

Z t Z tD

T Z


EMF: CME-FLARE CONNECTION

• Best-fit and good-fit solutions yield in close agreement with X-ray light curve.

• Predicted Sf is consistent with observation.

D = 1.3% Z0 = 2.5 x 105 km Sf = 4.25 x 105 km <E>max = 3.7 V/cm

( ) /pd t dt

12 September 2000

Chen and Kunkel (2010)


SENSITIVITY OF FLUX INJECTION TO HEIGHT DATA

D = 1.4% Z0 = 8 x 104 km Sf = 2.0 x 105 km

<E>max ~ 15 V/cm

Initial-value solution from Z0 to 1 AU

Chen and Kunkel (2010)

The main acceleration phase manifests Alfven timescale B0 and MT0

Must be internally generated by a model

The long-time trajectory is a stringent constraint on ( ) /pd t dt


CME-FLARE CONNECTION

• Demonstrated for several CME-flare events:

‒ The best-fit solutions constrained by height-time data alone yield —a physical prediction—in close agreement with ISXR(t) (temporal form)

‒ The height-time data contain no information about X-rays—agreement is significant

• Hypothesis and an interpretation

‒ is a potential drop (super Dreicer) particle acceleration and radiation physical connection between CME and flare particle acceleration

• Physical implications

‒ The time scale of ISXR(t) is in the height-time data—via the ideal MHD EFR equations

‒ The EFR equations capture the correct physical relationship between “M” and “HD”

• Test with another observable quantity

‒ Magnetic field at 1 AU as constrained by the observed CME trajectory data

( ) /pd t dt

(1/ ) ( ) /pemf c d t dt

NRL Solar Physics Division6.1 New Start Plasma Physics Division

• Best-fit solution is within 1% of the trajectory data throughout the field of view

• If Zdata(t) is used to constrain the EFR equations, the model predicts B1AU(t) correctly• Arrival time earlier than observed; in this case, a 3D geometrical effect (Kunkel 2012)

B A

Observed B1AU and 3D Geometry

STEREO Configuration 2007 Dec 24

[Kunkel and Chen 2010]

PROPAGATION OF CME and EVOLUTION OF CME B FIELD

Earth


SENSITIVITY OF B(1AU) TO SOLAR QUANTITIES

Dependence of B(1 AU) on injected poloidal energy

• Total poloidal energy injected:

• Vary the flux injection profile while keeping Up|inj unchanged

2 0

( ') ( ')1| '( ') 'p p

p injt d t

U d tL t d tc

D Bc dΦp/dt (ΔUp)totB(1AU) T(1AU) a(1AU)

[Gauss] [Mx/sec] [erg] [nT] [UT] [km]

0.84 -1.0 4.2 x 1018 9 x 1031 22 61 9.4 x 106

2.97 -1.0 3.6 x 1018 9 x 1031 22 61 9.4 x 106

2.61 -1.0 4.8 x 1018 9 x 1031 22 61 9.4 x 106

• |BCME| and arrival time at 1AU are not sensitive to the flux injection profile

• BCME field and arrival time are most sensitive to injected poloidal magnetic energyKunkel (PhD thesis, 2012)

Best fit


MAGNETIC FIELD AND TIME OF ARRIVAL OF CME AT 1AU

• Increase the total injected poloidal energy Up|inj by 10%

‒ Calculate the best-fit solution‒ Calculate B(1 AU) and time of arrival of CME at 1 AU‒ Determine the goodness of fit for each solution

D Bc dΦp/dt (ΔUp)tot B1AU T1AU a1AU

[Gauss] [Mx/sec] [erg] [nT] [hrs] [km]

2.87 -1.0 5.6 x 1018 1 x 1032 23 60 9.3 x 106

4.37 -1.0 4.9 x 1018 1 x 1032 24 59 9.1 x 106

2.26 -1.0 5.5 x 1018 1 x 1032 22 61 9.4 x 106



0.84 -1.0 4.2 x 1018 9 x 1031 22 61 9.4 x 106

2.97 -1.0 3.6 x 1018 9 x 1031 22 61 9.4 x 106

2.61 -1.0 4.8 x 1018 9 x 1031 22 61 9.4 x 106

Best fit

Constant Injected Poloidal Energy


B(1 AU) AND ARRIVAL TIME AT 1 AU: INFLUENCE OF Bc

• The overlying field Bc determines the initial Bp, initial energy, and Alfven time

• Expect the 1 AU arrival time and B(1 AU) to be sensitive to Bc

Sf

R

a



0.84 -1.0 4.2 x 1018 9.0 x 1031 22 61 9.4 x 106

3.50 -0.5 5.4 x 1018 7.2 x 1031 17.0 60 8.6 x 106

3.36 -1.5 6.8 x 1018 1.5 x 1032 26.1 62 1.0 x 107

0 0 0 0 0 0 0( / ) ln(8 / ),p c pB R a B R a


SUMMARY

The EFR model equations

• A self-contained description of the unified CME-flare-EP dynamics‒ Correctly replicates observed CME dynamics to 1 AU—a challenge for any CME model

• It can be driven entirely by CME data to compute physical quantities:

‒ — coincides with temporal profile of GOES SXR data (Chen and Kunkel 2010)

‒ B field and plasma parameters at 1 AU — in agreement with data (Kunkel and Chen 2010)

‒ B(1 AU) is not sensitive to the temporal form of ; it is sensitive to the total poloidal energy injected (Kunkel, PhD thesis, 2012; Kunkel et al. 2012)

Physical interpretations of • is the electromotive force—physical connection to flares

Implications –Space Weather• Given observed CME trajectory (position-time) data, it is possible to predict the

magnetic field at 1 AU—there is sufficient information (Kunkel, PhD, 2012)

• Accurate 1-2 day forecasting is possible if an L5 or L4 monitor exists

( ) /pd t dt

(1/ ) ( ) /pemf c d t dt

( ) /pd t dt

( ) /pd t dt


OPEN ISSUES

Energy Sources

• admits two distinct physical interpretations (Chen 1990; Chen and Krall 2003; Chen and Kunkel 2010)

‒ Coronal source: injection of flux from coronal field via reconnection (conventional)‒ Subphotospheric source: injection of flux from the solar dynamo (Chen 1989, 1996)

• Neither interpretation has been theoretically or observationally proven

‒ Reconnection: physical dissipation mechanisms and large scale disparity‒ Subphotospheric mechanism: none has been calculated

• Both are “external physics” in all current CME/flare models

( ) /pd t dt


OTHER MODELS

• The EFR model should be applicable to flux ropes with fixed footpoints

‒ models starting with flux ropes (Chen 1989; Wu et al. 1997; Gibson and Low 1998; Roussev et al. 2003; Manchester et al. 2006)

‒ arcade models producing flux ropes (e.g. Antiochos et al. 1999; Amari et al. 2001; Linker et al. 2001; Lynch et al. 2009)

• Does not apply to axisymmetric flux rope models—e.g., Titov and Demoulin (1999), Lin, Forbes et al. (1998), Kliem and Torok (2006)

‒ They do not correspond to simulations (e.g., Roussev et al. 2003; Torok and Kliem 2008)

• Mathematically, occurs in arcade models (e.g., Lynch et al. 2009)( ) /pd t dt

Titov and Demoulin (1999) Lynch et al. (1999)


PHOTOSPHERIC SIGNATURES?

• Assumptions:

‒ Coherent B field (space and time)‒ No dynamics‒

• Schuck (2010)

‒ Smaller A and longer‒ Same calculation (no dynamics)

AGU Fall (2001)

Lin et al. (2003)

1/V A t

t


• Schuck (2010)

‒ Falsified the “flux injection hypothesis”‒ Consistent with the “reconnection hypothesis”

• Starting point

‒ Specified coherent field and time scale‒ ‒ No subsurface source of poloidal flux‒ No dynamical equations of motion for “injection”‒ No gravity (e.g., no Parker instability)‒ No convection zone medium through which “injection” occurs‒ No photosphere (i.e., no photospheric signature)‒ No reconnection physics or dynamics

• No physical or mathematical basis to support either claim‒ A “Strawman” argument

• The calculation is the same as Forbes (2001)

OBSERVATIONAL SIGNATURES OF FLUX INJECTION

/ 4 , /c c S E B E V B 0


POLOIDAL FLUX INJECTION

• Poloidal magnetic field is mostly in region—incoherent in dynamics1

Chen (2012, ApJ)(1/ ) 0

0( )

c p

p

J B

J B


Initial Simulation: Chen and Huba (2006)

‒ 3D MHD code (Huba 2003)‒ A uniform vertical flux rope‒ Increase B field at the bottom‒ Introduce a horizontal flow (“convection” flow)‒ No gravity yet

DYNAMICS OF POLOIDAL FLUX INJECTION


PHOTOSPHERIC SIGNATURES

• Pietarila Graham et al. (2009) –current magnetogram resolution insufficient to resolve small-scale magnetic structures

• Cheung et al. (2010) –Simulation of an emerging flux rope; synthetic magnetograms

‒ Photospheric data show small bipoles; scales are much smaller than the underlying emerging flux rope

Cheung et al. (2010)


END


POST-ERUPTION ARCADES

Formation of Post-Eruption Arcades

Test the hypothesis that reformation of an arcade results from Establishes the physical connection between CME acceleration and flare energy release

EUV+H

Jc(t)

(1/ ) ( ) /emf pE c d t dt

Roussev et al. (2003)

( ) /pd t dtJc(t)

Quantities for comparison: temporal profiles

v. 22( ) ( )EUV c pI t J t d dt ( ) /SXR pI t d dt

CME Eruption at the Sun and Ejecta Magnetic Field at 1 AU

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