The May 1997 and May 1998 MURI events

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The May 1997 and May 1998 MURI events

• George H. Fisher
• UC Berkeley

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May 12 1997

• Classic 2-ribbon flare occurring in NOAA AR 8038
  at 0445 UT
• Halo CME seen 1-2 hours later
• (partial) filament eruption
• Global solar magnetic configuration is quite
  simple
• Magnetic data poor temporal coverage, coarse
  spatial resolution
• In MURI teams Yang Liu (Stanford) is doing most
  of the work on this event

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Global magnetic configuration around May 12, 1997
(pfss model)

• Overall global magnetic configuration is simple
  just one active region on the disk at the time of
  the flare/CME.

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Magnetic Evolution of AR 8038 over 3 days

• Active region appears to be mature and starting
  to decay, with apparent flux cancellation

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May 12, 1997 Evolution seen in H?

• 2-ribbon flare
• Partial filament disappearance
• X-ray importance C-class

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May 12 1997 X-ray evolution

• Before flare sigmoid shaped arcade
• Flare decay classic candle-flame shaped arcade

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May 12, 1997 Double dimming, EIT wave

• Double-dimming occurs after flare, roughly at
  ends of 2-ribbon flare arcades.

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May 12 1997 LASCO C2 images

• Wimpy halo event seen 2 hours after the
  2-ribbon flare

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Interplanetary Data for the May 12 1997 event

• Some hidden text

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May 1, 1998

• Active region 8210 produced a long series of
  flares and CMEs as it rotated across the disk.
  Our focus is several small flares / CMEs
  occurring on May 1, 1998 because of very high
  quality vector magnetic field observations taken
  that day.
• Overall solar configuration was not so simple
  8210 appears connected to an active region across
  the equator via trans-equatorial loops

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Global magnetic configuration around May 1, 1998
(pfss model)

• AR 8210 appears to be magnetically connected to a
  northern hemisphere AR and is also adjacent to a
  low-latitude coronal hole

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24 hours of high cadence MDI evolution of AR
8210 on May 1 1998

• Flux emergence above and to right of sunspot
• Clockwise rotation of sunspot
• Flow of positive polarity on left of spot toward
  lower right

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Non-constant ? force-free field fit to AR 8210
(Regnier)

• Uses vector magnetogram data from IVM instrument
  on Haleakala data averaged for a 15 minute
  cadence

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Models of the emission from AR 8210 (Loraine
Lundquist)

• Start from Regniers FFF solution
• Assume a heating function Q B/L on each field
  line
• Solve energy balance equation
• Compute emissivity and make false image

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H? evolution of AR8210 on May 1, 1998

• There are several filaments associated with this
  active region, which appear to be constantly
  evolving
• There appears to be a 2-ribbon flare around 2340
  UT

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X-ray evolution of AR 8210 on May 1, 1998

• Note simultaneous flickering of the two active
  regions, plus hint of transequatorial loops
• Note the repeated activation of the arcade of
  loops on the LHS of the active region

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EIT evolution of AR 8210 on May 1, 1998

• Note repeated brightenings along LHS of active
  region adjacent to coronal hole
• This evolution described by Sterling Moore in
  their paper on EIT crinkles as repeated
  reconnection of closed field lines with open
  field lines in the hole

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Interplanetary Data for May 1, 1998