Coronal loop oscillations and diagnostics with HinodeEIS

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Coronal loop oscillations and diagnostics with
Hinode/EIS
Youra Taroyan Thanks to T. Wang, S.
Bradshaw Department of Applied
Mathematics University of Sheffield Hinode
Meeting, Dublin 2007
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SXT and SUMER observations of hot loop
oscillations
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SUMER measurements Results of the
line profile synthesis
FeXIX CaXV CaXIII
FeXIX CaXV CaXIII
EIT 195Å
Taroyan et al., ApJ 2007
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• Confirm that the hot loop oscillations represent
  standing (slow) acoustic waves
• The oscillations are set up by a footpoint
  microflare its total energy and duration are
  estimated
• The time-distance profile of the heating function
  reproduced

1.5x1027 erg
Why only hot loops?
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Thermal conduction Heating rate Radiation
1D loop modelling (HYDRAD)
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Standing waves
Propagating waves
Hydrodynamic evolution of the loop
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Synthesized Hinode/EIS observations
Selected lines -FeX 190Å, FeXI 188.23Å, FeXII
195Å Imaging mode - 40 slot Spectroscopy mode
1 slit Loop location disc centre
Orientation south-north
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Standing waves
Propagating waves
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Standing waves
Propagating waves
FeXII 195Å, 1 FeXI 188.23Å, 1
FeX 190Å, 1
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• Problem
• The diagnostic methods currently used in coronal
  seismology rely on the presence of coherent
  standing/propagating waves
• The presence of such waves is not guaranteed!
• New method

Analysis of Doppler shift time series as a
diagnostic tool (Taroyan et al., AA 2007)
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Analysis of Doppler shift time series as a
diagnostic tool
x
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Intensity time series?
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• Summary
• Yohkoh/SXT and SoHO/SUMER observations of hot
  loop oscillations combined with forward modelling
  provide important information about heating
• EIS observations of standing and propagating slow
  (acoustic) waves are synthesized using a
  selection of available spectral lines and
  slits/slots
• The waves are best seen and identified in
  spectroscopy mode observations
• The intensity oscillations are subject to phase
  variations and therefore the Doppler shift time
  series are suggested to be used for diagnostic
  purposes