A new view: flares and CMEs

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A new view flares and CMEs
UCL Department of Space and Climate
Physics Mullard Space Science Laboratory
???

• Louise K Harra
• Hinode EIS website http//msslxr.mssl.ucl.ac.uk
  8080/SolarB/

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Science goals - Determine how the corona is
heated in active regions and in the quiet
Sun - Establish the mechanisms that give
rise to transient phenomena, such as flares
and CMEs - Investigate the processes
responsible for energy transfer in the quiet
Sun
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Flares since the Hinode launch

• We launched close to solar minimum - still during
  commissioning we have the famous December flares!
• 4 X-flares, 15 M-flares, many C-flares.

See Simon Plunketts talk after lunch! The STEREO
view.
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What do we expect from the standard flare model?

• Inflow and outflow
• Evaporation
• Field line shrinkage
• Increase in footpoint separation

Questions to be answered

• What triggers the flare in the first place?
• Is the standard model correct?
• What is the global impact of the flare on its
  surroundings?

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Evolution of magnetic fields before large flares

• The 13th Dec flare was an X3.4 class flare.
• The flare seemed to occur at the collision site
  between large, opposite polarity umbrae.
• Kubo et al., 2007

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• Many Ca II H loops appear between the opposite
  polarity umbrae before the large flare.
• There is 1 day between the elongated structure of
  opposite polarity appearing and the X-flare
• Magnetic helcities of the opposite sign are
  supplied into the colliding region.
• Consistent with the reverse shear model of Kusano
  et al. 2004

See Shibasaki sans talk today Particle
acceleration for Dec 13 flare. Rim Turkmanis
talk tomorrow Particle acceleration in the
footpoints of stressed loops. Inoue sans talk
today 3-D coronal structure in
AR10930 Magara-sans talk tomorrow Sunspot
motion and its relation to activity
Kubo et al., 2007
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Can a kink instability be a trigger?
This is the process where twist is abruptly
converted into writhe.
Williams et al. (2005)
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13th December filament eruption

• Williams et al. (2007) analyse the flows around
  the filament length before the flare.
• Consistent with the expansion of a twisted flux
  rope due to either the MHD helical kink or torus
  instability.

See Sterling sans talk today onset stage of
filament eruption Davids talk today pre-flare
destabilisation of a filament Hudson sans talk
tomorrow physical conditions of coronal
structures about to flare Yokoyama-sans talk
tomorrow Observations of magnetic structure of a
dark filament.
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A black and white-flare?

• X1.5 flare on 14 December 2006 observed by SOT
  and TRACE in WL and in Fe I.
• Flare ribbon morphology in g-band and Fe I
  identical and a spatially correlated sub-set of
  the TRACE WL emission. Magnetic reversal also
  observed within WL ribbons -gt photospheric origin
• G-band light curves show clear pre-flare dip -gt
  black-light flare??
• Matthews and Bone - go and see the poster!

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Evolution of the sheared core in X-rays (Su et
al. 2007)
XRT observations of sheared field formation From
0019 UT on Dec 10 To 1243 UT on Dec 12

• SOT observations of
• Emerging flux
• West-to-east Motion
• CCW Rotation
• in the Lower sunspot

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X 3.4 flare on 2006/12/13
Part of the sheared cored field erupted, while
part of them stayed behind. Seems consistent with
Moore et al., 2001
See Marc DeRosas talk today Non-linear force
free field modeling of a large AR.
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The flare itself

• The cooler emission lies below the hotter
  emission

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Cusp and Post-Flare Loops
Fe X contour (1MK) Fe XIV image (2MK)
Fe XIV contour (2MK) Ca XVII image (5MK)
Image Fe XV 284 Contour He II 256
Image Ca XVII 192 (,Fe XI, O V) Contour Fe
XV 284
Hara et al., 2007
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RHESSI and Hinode flare observations

• RHESSI thermal sources located above EIS loops
  near the top of XRT loops where imaging is
  available
• RHESSI non-thermal sources near XRT footpoints
  (14 December flare).
• RHESSI sources hotter than the loops observed by
  Hinode (12-25MK)

See Laura Bones poster
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Field Line Shrinkage
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Field Line shrinkage

• Reeves et al. (2007) show field line shrinkage
  both on the limb AND on the disk. Speeds of 45
  km/s have been measured.
• 17th Dec flare had 27 shrinkage.
• Seen well into the decay phase.

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• Flare at the limb seen in Ca XVII
• unusual flows are seen in the loops..
• Hara et al., 2007

?
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The mysterious region above the loop top
FWHM126 km/s
See Len Culhanes talk tomorrow observations of
17th Dec flare. Watanabe-sans talk tomorrow on
Fe XIII fine structures in flares.
FWHM155 km/s
We can now observe the region where reconnection
may be occurring..
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Sigmoids!

• Sigmoids are important since they have been shown
  to have a close relationship to CMEs.
• McKenzie and Canfield are studying a sigmoid with
  XRT.
• The sigmoid lasts 2 days before eruption.
• Seems to be consistent with a twisted flux rope
  emerging beneath the photosphere.

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Onset of Coronal Mass Ejections

• Harra et al., 2007

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Onset of CMEs

• The source regions are CMEs are related to
• dimming regions - but what is the physical
  process?

EIS - FeXV
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The source region of the CME is seen
Before
After

• Before faint long loops seen at the end of the
  active region - outflows observed - tens km/s
• After dimming observed - both small loops at the
  edge of the AR and the long, faint loops are
  disrupted. Stronger outflows up to 50 km/s seen.
• We can now see structure and measure
  quantitatively the source regions of CMEs.

See Ron Moores talk today - on width of a CME
and the source of the explosion. Gemma Attrills
talk tomorrow Physical properties of coronal
waves and associated dimmings
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The impact of flares on the surroundings 13th
December
Imada et al., 2007
FeX
FeXI
CaXVII
FeXII
FeXIII
HeII
FeXIV
FeXV
FeVIII
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The large flare on the 13th Dec causes
significant responses away from the flare site -
including inducing large outflows. Imada et al.,
2007
See Imada-sans talk today upflow in a plage
region associated with an X-class flare. Kelly
Korrecks talk X-ray luminosity of flares
related to magnetic flux and the solar wind.
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Velocity vs Temperature
Dashed lineSound Speed
FeXV
FeXIV
Upward Velocity km/sec
FeXIII
FeXII
FeX
FeXI
FeVIII
OV
HeII
Log Te
The upflows are very sensitive to temperature!
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What we can now measure.

• We can see the complexity of the magnetic field
  building up to flares.
• We can measure dynamics (and turbulence) of
  flaring loops.
• We can measure the twist in filaments before
  eruption.
• We can measure dimming quantitatively.

We are progressing to a much greater
understanding of the dynamical Sun even in solar
minimum!