The May 1997 and May 1998 The May 1997 and May 1998 MURI eventsMURI events

George H. Fisher

UC Berkeley

May 12 1997May 12 1997

Classic 2-ribbon flare occurring in NOAA AR 8038 at ~ 04:45 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

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

Magnetic Evolution of AR Magnetic Evolution of AR 8038 over 3 days:8038 over 3 days:

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

May 12, 1997: Evolution seen in HMay 12, 1997: Evolution seen in H

2-ribbon flare Partial filament

disappearance X-ray

importance: C-class

May 12 1997: X-ray evolution:May 12 1997: X-ray evolution:

Before flare: sigmoid shaped arcade

Flare decay: classic candle-flame shaped arcade

May 12, 1997: Double dimming, EIT waveMay 12, 1997: Double dimming, EIT wave

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

May 12 1997: LASCO C2 imagesMay 12 1997: LASCO C2 images

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

Interplanetary Data for the May 12 1997 eventInterplanetary Data for the May 12 1997 event

Some hidden text

May 1, 1998May 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

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

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

HH evolution of AR8210 on evolution of AR8210 on May 1, 1998May 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 23:40 UT

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

EIT evolution of AR 8210 on EIT evolution of AR 8210 on May 1, 1998May 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

Interplanetary Data for May 1, 1998Interplanetary Data for May 1, 1998