Culmination of the flare activity of Group 10786 in July 2005: X-Ray observations from near-mars and near-earth orbits

A detailed study of two major solar flares that occurred in Group 10786 at the time of its disappearance behind the western limb is presented. The flares of July 14, 2005 were previously studied fairly poorly, as no RHESSI hard X-ray observations were available for themaxima of the twomost powerful of these flares. Observations carried out using the HEND equipment (on the Mars Odyssey spacecraft) developed at the Institute for Space Research in Moscow are used here to fill this gap. In the first flare, an intense, impulsive burst occurred at 07:23 UT, about 1.5 h after the onset of a weak, prolonged event. While processes in the neighborhood of the northern spot dominated in the flares of July 5–9, a powerful impulsive energy release on July 14 emerged when the flare process that originated in the North reached the southern spot. Our analysis of the flare activity of this medium-sized group reveals a gradual enhancement of the flare activity and a strong interaction between the acceleration above the magnetic-field neutral line and in the immediate vicinity of the spots. At the time of the culmination of the flare activity in the group on July 13 and 14, the pattern of nonstationary processes changes: fast coronal mass ejections form after a series of impulsive energy-release events. Spacecraft observations of the burst of July 14 after 11 UT at points separated in longitude (on RHESSI and Mars Odyssey) revealed clear anisotropy of the flare emission at energies exceeding 80 keV.