Magnetic Energy Release and Transients in the Solar Flare of 2000 July 14

Abstract

High-resolution observations of a large solar flare on 2000 July 14 ("Bastille Day Flare") from the Michelson Doppler Imager instrument on the SOHO spacecraft reveal rapid variations of the magnetic field in the lower solar atmosphere during the flare. Some of these variations were irreversible, occurred in the vicinity of magnetic neutral lines, and likely were related to magnetic energy release in the flare. A surprising result is that these variations happened very rapidly on the scale of 10-15 minutes in a large area of ~50 Mm² at the beginning of the flare. Other, more localized and impulsive magnetic field variations somewhat similar to "magnetic transients" observed by Zirin and coworkers were accompanied by impulses in continuum intensity and Doppler velocity. These impulses have dynamic characteristics similar to Ellerman's "bombs" and Severny's "mustaches" and were probably caused by high-energy particles bombarding the solar surface.