Advisors: Richard Canfield & Loren Acton
It is known that Coronal Sigmoids -- sinuous structures seen in X-ray solar images as bright transient S or inverse-S shapes -- herald solar eruptions (Coronal Mass Ejections, or CMEs). Debate rages about the physical origin of this association. A recent study of a limited sample of sigmoids, numbering just four events, points to kinking of twisted magnetic fields as a possible component of these eruptions. Fortunately, we have a large database of X-ray observations from the Yohkoh mission, which observed the X-ray sun for about a decade from 1991 to 2001. We have searched this database in past studies, and have found 107 individual sigmoids that were observed by the Soft X-Ray Telescope with the full available spatial resolution. Many of these sigmoids are known to have erupted, so we intend to subject the results of the limited sample to a more compelling statistical test.
The work to be done consists of making movies of those of the 107 sigmiods to identify those for which eruptions were observed in progress, and then search these visually for evidence of the kinking motion and other signatures of twisted fields. This is a project for a student with at least some programming skills and interest in addressing one of the most active issues of current solar physics. The project will make extensive use of our unix computer cluster, the IDL programming language, and the on-line database of X-ray images from the Yohkoh mission. The student can expect to learn sophisticated methods for analyzing imaging data from NASA spacecraft, as well as the phenomenology and physics of both sigmoids and CMEs.