LongDuration Flare Observed with Hinode EIS

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Long-Duration Flare Observed with Hinode EIS

• H. Hara, T. Watanabe, L. Harra, L. Culhane, P.
  Cargill,
• G. Doschek, J. Mariska

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Introduction

• Folowing Yohkoh (e.g. Tsuneta et al., 1992), many
  imaging observations suggest the existence of
  magnetic reconnection processes in the solar
  corona
• Magnetic reconnection is thought to be a key
  process in long-duration event flares (LDE).
• This study reports the first LDE observation with
  Hinode EIS
• EIS has the capability to observe phenomena
  related to magnetic reconnection using
  spectroscopic observations
• Work in progress
• may lead to a direct demonstration of
  reconnection velocities
• clarify any role of non-thermal processes

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Other Observations

• SOHO
• -CDS with13 min cadence raster
• - EIT
• - LASCO
• TRACE
• RHESSI
• H? and He I 10830 Å Doppler image at Mauna Loa
• LASCO CME

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GOES and LASCO Data

• C-class flare
• Temperature increase observed a few hours before
  the flare onset
• Weak (micro-) flaring activity 7-10 hours before
  the flare onset
• Related CME observed in LASCO

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2006 Dec 17 Flare

• First LDE with cusp-shaped loops observed with
  EIS
• Observed in Active Region raster scan study
• - long exposure duration of 30sec
• - large area scanned
• - hot solar flare lines not included
• No other active regions on the sun

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EIS Observation Nine Emission Lines
?
1615 UT
1710 UT
1830 UT
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Cusp and Post-Flare Loops
Image Fe XV 284.2 Å Contour Fe X 184.6 Å
Image Ca XVII 192.8 Å (Fe XI, O V) Contour
Fe XV 284.2 Å
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XRT movie

• No XRT, EIS or RHESSI data at initial phase
• However event does not appear to be impulsive

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EIT Movies

• Large-scale loop gradually expanding before
  flare onset
• Inflowing motion observed.

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Observation in Ca XVII with EIS
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Observation in Ca XVII with EIS
Ca XVII O V 192
Intensity
log I DN
FWHM km/s
Fe XI contribution is largely removed by
subtraction. Instrumental line width is not
subtracted.
Line intensity ratio for temperature estimation
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FWHM in Cusp Structure
FWHM126 km/s
FWHM136 km/s
When this difference is explained by
temperatures, ?T 2.3 MK. When this difference
is explained by nonthermal velocity, ?? 31 km/s
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RHESSI Thermal Hard X-ray Source

• RHESSI thermal spectrum, Te 15 MK (Bone et al.
  this meeting)
• Bright Ca XVII feature, Te 6 - 7 MK at peak of
  G(Te)
• - difference 8 MK
• Emission measures
• - Ca XVII EM 2.5.1048
• - RHESSI 1.0. 1047

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Motion of Features 17th December Flare

• Significant field line shrinkage
• is also observed
• (Reeves et al., 2007, Submitted, Ap.J.)

Associated RHESSI source also rises slowly
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Intensity, Doppler, and FWHM from EIS
Fe XII 195
FWHM
Doppler
Intensity
(contains instrumental width)
km/s
km/s
log N (photons)
scanning direction with time increasing
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Intensity, Doppler, and FWHM from EIS
Fe XV 284
FWHM
Intensity
Doppler
(contains instrumental width)
log N (photons)
km/s
km/s
scanning direction with time increasing
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Summary

• Positional relationship between flare arcades and
  post-flare loops is clearly observed
• Cusp-shaped flare loops have broader line width
  component in their outer edges
• - Ca XVII ions have larger kinetic energy
  towards edges
• Plasma motions along post-flare loops are
  observed along
• with field line shrinkage
• Post-flare loop structure is complex
• - difficult to interpret flow velocities and
  line broadenings
• Some spectroscopic evidence of reconnection
  inflow is observed by EIS (needs confirmation)

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END OF TALK
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CDS
loop top of post-flare loop first appears in O V.
Cusp structures also seen in CDS.
Blue shift is observed at the onset of flare.