PowerPoint Presentation Magnetic Reconnection and Mass Acceleration in Solar Flares and Coronal Mass

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Solar Active Regions and Explosions Journey
from the center of the sun - Zirker
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Solar Active Regions active regions are where
the solar atmosphere is most active, or hotter
and more dynamic. These are regions of
concentration of magnetic fields.
ARs across the spectrum (TRACE)
Looking through the suns atmosphere (MSU)
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Magnetic fields are discovered and measured by
Zeeman effect, or split and polarization of
magnetically sensitive spectral lines ?????gB
measuring B in three components - vector B - from
Stokes I/Q/U/V profiles
Magnetic fields are the source of solar activity.
Magnetic fields deviating from potential fields
contain free energy to fuel energetic solar
activities. gt current free, force free, and
non-force-free magnetic fields What is a
potential field look like? And what is a sheared
field? http//bbso.njit.edu/qiuj/vmg/vmg1.html
A vector magnetogram
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We know little of the suns magnetic field in the
corona, and mostly reconstruct it by
extrapolation.
model coronal magnetic field of the whole sun.
(TRACE)
(Y. Liu)
Or we may use microwave observations to map
the coronal magnetic structure in active regions.
Lee et al. 1998
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flares a spectacular form of violent solar
energy release.
a large flare observed in different
wavelengths (Qiu et al.)
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The Ramaty High Energy Solar Spectroscopy Imager
(RHESSI) launched in 2002 provides unique chance
to study flares on all scales.
(Qiu et al. 2005)
flare number density wrt peak hard X-ray photon
count rate detected by RHESSI
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Most flares occur in active regions where
magnetic fields concentrate and are
complex. They are located at where the polarity
of magnetic fields reverses.
X-ray in magnetogram
(Liu et al. 2005)
(Qiu et al. 2005)
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Flares are reconnection events.
Magnetic reconnection is an efficient mechanism
to release a large amount of magnetic energy in a
short time, as in the case of solar flares.
(DeFrost)
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Masuda flare hard X-ray source above the loop
top (Masuda et al. 1994)
Here put a couple of figures from
satellite Observations.
YOHKOH
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soft X-ray jet as indication of reconnection
outflow (Shimizu 1994)
soft X-ray high temperature ridges along outer
or newly formed loops (Tsuneta 1996)
YOHKOH
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Magnetic reconnection is the driver of solar
flares.
?
? E field
front view (T. Forbes)
Magnetic reconnection rate is deduced by
measuring expansion of flare ribbons across
magnetic fields.
top view (BBSO)
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Coronal mass ejections are often accompanied by
filament eruptions and flares.
(SoHO)
They are all driven magnetically.
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some CME-flare models
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RHESSI/OVSA observations of flares
(Qiu et al. 2005)
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non-thermal signatures of flares
Hard X-ray
microwave
(Qiu et al. 2005)
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About energetic particles electric field
acceleration or stochastic acceleration, such as
by shocks?
Foot-point or loop-top source? Thermal or
Non-thermal? Thin target or Thick target?
(Qiu et al. 2004)
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An example particle acceleration by electric
field and then collapsing magnetic traps (Somov
Kosugi 1997)
Evolving magnetic traps form between shock fronts
and closed magnetic loops formed by successive
magnetic reconnection. Pre-accelerated (by
electric field) electrons are further accelerated
in the traps via a first Fermi mechanism, and
then precipitate to emit at foot-points.