Supraarcade Downflows in the 21 April 2002 X flare

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Supra-arcade Downflows in the 21 April 2002 X
flare

• David McKenzie
• Davina Markiewicz-Innes
• Tong Jiang Wang

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Archetypical downflows, 20 Jan 1999

• Traced by dark blobs moving into top of arcade
• Speeds 90-500 km/s
• Decelerating blobs
• Later, some x-ray-bright shrinkages noted

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TRACE downflows,21 Apr 2002

• Traced by dark blobs
• Speeds 85-240 km/s
• Decelerating
• Spatial resolution!

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TRACE SUMER

• SUMER in C II, Fe XII, Fe XXI
• Slit intercepts several downflows

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Time-space plotdark in all 4 temperatures
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Density of dark features

• Lack of C II signal suggests less than 109 cm-3
  at 23 000 K
• H? blobs above arcade must be faint
• Extinction of 195 Å requires 3x1010 to 1x1011
  cm-3

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Spoke reactions

• Spokes react when blobs move downward

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Spoke oscillations

• Reaction of spokes ? blobs move through spokes
• If MHD waves, then indicates Alfven speed

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Conclusions

• Dark SADs still have unknown density
• Consistent with magnetic shrinkage, or with
  falling cool material
• If cool material, then temperature is hard to
  understand, since not viewed in emission
• Motion is through the spokes, not in front of