Modeling and Measuring the Flux Reconnected and Ejected by the Two-ribbon Flare/cme

Observations of the large two-ribbon flare on 7 November 2004 made using SOHO and TRACE data are interpreted in terms of a three-dimensional magnetic field model. Photospheric flux evolution indicates that −1.4 × 10 Mx of magnetic helicity was injected into the active region during the 40-hour build-up prior to the flare. The magnetic model places a lower bound of 8×10 ergs on the energy stored by this motion. It predicts that 5 × 10 Mx of flux would need to be reconnected during the flare in order to release the stored energy. This total reconnection compares favorably with the flux swept up by the flare ribbons which we measure using high time cadence TRACE images in 1600 Å. Reconnection in the model must occur in a specific sequence which would produce a twisted flux rope containing significantly less flux and helicity (10 Mx and −3 × 10 Mx respectively) than the active region as a whole. The predicted flux compares favorably with values inferred from the magnetic cloud observed by Wind. This combined analysis yields the first quantitative picture of the flux processed through a two-ribbon flare and CME.