Evolution of Pre-Eruption Sigmoids into Post-Eruption Arcades in Suspected CME Source Regions

Alphonse C. Sterling

Abstract

There is growing evidence that S-shaped or inverse-S shaped sigmoid structures in the soft X-ray (SXR) solar corona are the source regions of at least some Coronal Mass Ejections (CMEs). These SXR "sigmoids" mark the presence of non-potential magnetic "core field" structures which erupt to form a portion of the CME. After eruption, these source regions take the form of more nearly potential field arcades, often with a cusp structure visible in SXRs. An understanding of the evolution from the pre-eruption structures to the post-eruption structures is a key element in untangling the mechanism underlying the eruption process. In this work, we examine details of this evolution for several eruptive events, using high cadence data from the Soft X-ray Telescope (SXT) on Yohkoh. In particular we study the spatial relationship between the pre-eruption sigmoid and the post-eruption arcade, considering how well the actual cases fit the standard opening/reclosing 3D magnetic field picture for ejective flare/CME events.

Authors: Alphonse C. Sterling, Ron L. Moore

Organization: NRC/MSFC
     Telephone: 256-544-3324
           Fax: 256-544-5862
        e-mail: alphonse.sterling@msfc.nasa.gov
       Address: SD50/Space Science Division
   Marshall Space Flight Center
   Huntsville, Alabama, 35812