THE MORPHOLOGY OF FLARE PHENOMENA, MAGNETIC-FIELDS, AND ELECTRIC CURRENTS IN ACTIVE REGIONS .2. NOAA ACTIVE REGION 5747 (1989 OCTOBER)

In this paper we describe the morphology of energetic electron precipi tation and high-pressure coronal flare plasmas of three flares relativ e to the vector magnetic field and vertical electric currents that we observed in NOAA Active Region 5747 in 1989 October. Using Halpha imag ing spectroscopy, we have identified the chromospheric sites of intens e nonthermal electron precipitation and high coronal pressure during t hese flares. Using the full Stokes profiles of two photospheric Fe I l ines (6301.5 and 6302.5 angstrom), we have derived vector magnetograms for a period of 5 consecutive days, during which these flares occurre d. From these photospheric magnetograms, we have determined the sites of the major vertical currents in this region. We have co-aligned the Halpha spectroheliograms with the vector magnetograms using continuum images of sunspots, which enables positional accuracy of a few seconds of arc. We find that during the gradual phase, the regions of the Hal pha flare that show the effects of enhanced pressure in the overlying corona often encompass extrema of the vertical current density. This i s consistent with earlier work showing a close relationship between Ha lpha emission and line-of-sight currents. However, the sites of precip itation of nonthermal electrons into the chromosphere lie close to the magnetic neutral line, on the shoulders of vertical current channels, rather than at vertical current maxima. This result is generally inco nsistent with earlier works' support of current-interruption models su ch as that of Alfven & Carlqvist (1967), except insofar as they apply to nearly horizontal currents. Our data are consistent with the overal l morphology and evolution described by erupting-filament models such as those of Kopp & Pneuman (1976) and Sturrock (1989). The possibility that flares accelerate energetic electrons in strong nearly horizonta l current channels remains to be investigated.