Transcript AR Structural Changes during a CME launching

Active-region magnetic
structures and their
perturbations by flares
H.S. Hudson
SSL/UCB
MRT workshop, August 10, 2004
Outline
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Description of a solar active region
Magnetic structure
Waves, oscillations, and restructuring
RHESSI observations of eruptive flares
MRT workshop, August 10, 2004
TRACE 171A view of an active region,
courtesy LMSAL “cool stars” Web material
MRT workshop, August 10, 2004
Mechanical properties of an
active region in the corona
• Flares and CMEs are magnetically driven,
according to consensus, from energy stored in the
corona
• In such conditions, (low plasma b), the
mechanical stresses can be represented as a
pressure and a tension
• Dissipation is normally slow
• The volume is electrically equipotential except for
the Rosseland-Pannekoek potential
MRT workshop, August 10, 2004
CH
G. A. Gary, Solar Phys. 203, 71 (2001)
MRT workshop, August 10, 2004
What are the loops?
• The loops show the direction of the magnetic field
• The X-ray visibility of the corona is a monotonic
increasing function of the gas pressure
• In an active region, the loop dimensions are
typically smaller than the scale height
• The footpoints of a loop lie in a transition layer at
the appropriate pressure
• The magnetic field must be slightly depressed in
the visible loops
MRT workshop, August 10, 2004
Lundquist et al., SPD 2004
MRT workshop, August 10, 2004
NOAA 10486, Haleakala IVM data, |B| cube
Scaled
Not scaled
Roumeliotis-Wheatland-McTiernan method
pixel size ~3000 km
MRT workshop, August 10, 2004
AR8210 courtesy J. McTiernan
MRT workshop, August 10, 2004
Conjecture: Most of the free energy in an
active region is concentrated very near its base
MRT workshop, August 10, 2004
The normal state of the activeregion corona is an equilibrium
• An equilibrium system will oscillate around
its rest configuration if perturbed slightly
• We observe coronal oscillations via
spectroscopy, photometry, and in movies
• The oscillations have small amplitudes and
can be studied via MHD theory
MRT workshop, August 10, 2004
Kink-mode oscillations
• Flare waves associated with metric type II
bursts often (12/30 cases) appear with
TRACE loop oscillations
• These oscillations allow us to study the
equilibrium state of the non-erupting part of
the corona
MRT workshop, August 10, 2004
Aschwanden et al., Solar Phys. 206, 99 (2002)
MRT workshop, August 10, 2004
Narukage et al., PASJ 56, L5 (2004)
MRT workshop, August 10, 2004
SUMER’s oscillations
Wang, T. J. et al.,
ApJ 574, L101 (2003)
MRT workshop, August 10, 2004
Yohkoh’s oscillations (BCS)
Mariska, J. et al., SPD poster (2004)
MRT workshop, August 10, 2004
QuickTime™ and a
Photo decompressor
are needed to see this picture.
Schrijver et al., Solar Phys. 206, 69, 2002
MRT workshop, August 10, 2004
Three things the movie showed
• Early inward motions, prior to the eruption
• Dimming - the CME starting off
• Excitation of coupled normal modes in the
arcade
• (arcade blowout)
MRT workshop, August 10, 2004
SXT observations of the blow-out of an
X-ray “loop prominence system”
MRT workshop, August 10, 2004
Studying coronal equilibria
• On large scales the corona tends be stable
• We can study the equilibrium states via the
oscillations; there are several modalities
• Propose to use “instrumented hammer”
approach to characterize eigenstates
• Propose to study before/after equilibrium
states using FASR and Solar-B
MRT workshop, August 10, 2004
H. Wang et al.,
ApJ 576, 497 (2002)
MRT workshop, August 10, 2004
Magnetic challenge: Can any existing
model of a flare or CME properly describe
the change in the coronal magnetic field?
MRT workshop, August 10, 2004
Cartoon showing magnetic implosion
Post-event field
Pre-event field
Isomagnetobars
Limb
Hudson & Cliver, JGR 106, 25,199 (2001)
MRT workshop, August 10, 2004
Conclusions
• Unlike the cosmologists, we don’t have a
standard model for a flare/CME - we do
have cartoons, though:
http://solarmuri.ssl.berkeley.edu/~hhudson/c
artoons/
MRT workshop, August 10, 2004
Serious conclusions
• Extrapolation techniques to learn about the coronal
magnetic field are inherently flawed
• It will be better in the future to assimilate more precise
methods, such as
- TRACE coronal imagery (direction of B)
- FASR gyroresonance surfaces (magnitude of B)
- Mechanical models (matching eigenfrequencies)
MRT workshop, August 10, 2004
From the Flare/CME Cartoon Archive
http://solarmuri.ssl.berkeley.edu/~hhudson/cartoons/
MRT workshop, August 10, 2004
Anzer-Pneuman, 1982
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Null?
Separatrices?
MRT workshop, August 10, 2004
Forbes,
JGR 105,
23,153, 2000
Gallagher,
P. T.,
personal
communication
2004
MRT workshop, August 10, 2004
QuickTime™ and a
Photo decompressor
are needed to see this picture.
MRT workshop, August 10, 2004
RHESSI observations of
early inward motions
MRT workshop, August 10, 2004
Sui et al., 2004
MRT workshop, August 10, 2004
Sui et al., 2004
MRT workshop, August 10, 2004