Solar Physics Division Meeting 2000, June 19-22
Session 14. Flares and Transients
Oral, Chair: P. L. Bornmann, Thursday, June 22, 2000, 11:00am-12:00noon, 1:30-2:30pm, Forum

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[14.05] Internal and External Reconnection in a Series of Homologous Solar Flares

A. C. Sterling (NRC/MSFC), R. L. Moore (MSFC)

Using data from the Extreme Ultraviolet Telescope (EIT) on SOHO and the Soft X-ray Telescope (SXT) on Yohkoh, we examine a series of morphologically homologous solar flares occurring in NOAA AR~8210 over May 1---2, 1998. An emerging flux region (EFR) impacted against a sunspot to the west and next to a coronal hole to the east is the source of the repeated flaring. An SXT sigmoid traces the EFR's neutral line at the site of the initial flaring in soft X-rays. In EIT, each flaring episode begins with the formation of a crinkle pattern external to the EFR\@. These EIT crinkles move out from, and then in toward, the EFR with velocities ~20~km~s-1. A shrinking and expansion of the width of the coronal hole coincides with the crinkle activity, and generation and evolution of a postflare loop system begins near the time of crinkle formation. Using a schematic based on magnetograms of the region, we suggest that these observations are consistent with the standard reconnection-based model for solar eruptions, but modified by the presence of the additional magnetic fields of the sunspot and coronal hole. In the schematic, internal reconnection begins inside of the EFR-associated fields, unleashing a flare, postflare loops, and a CME\@. External reconnection, occurring between the escaping CME and the surrounding fields, results in the EIT crinkles and changes in the coronal hole boundary. Our inferred magnetic topology is similar to that suggested in the \lq \lq breakout model" of eruptions [Antiochos, 1998], although we cannot determine if the ultimate source of the eruptions in this case is due to the breakout mechanism or, alternatively, is primarily released by the internal reconnection.


\noindent ACS is an NRC---MSFC Research Associate

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