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Session 36 - Solar Activity.
Display session, Tuesday, June 11
Very Large Array (VLA) observations of the Sun at 20 and 91 cm have been combined with simultaneous Yohkoh SXT images in order to study the relationship between Type I noise storms and morphological changes in associated coronal magnetic loops. During one period of observation, VLA 91 cm snapshot maps show anti-correlated fluctuations in widely-separated noise storm sources which are connected by faint, trans-equatorial 91 cm and soft X-ray emission. This suggests that the two underlying active regions were joined by a large-scale magnetic loop which confined and channeled energetic particles from one region to the other, leading to the onset of noise storm emission in one of them. On another day, the 91 cm continuum component was spatially resolved from a group of associated Type I bursts. While the continuum source remains stationary, the locations of the bursts vary by as much as 50" along the major axis of the continuum source which lies above an arcade of soft X-ray loops. Time sequences of Yohkoh SXT images show a contraction of coronal loops prior to the onset of this group of bursts as well as the brightening of an X-ray source lying at the apparent footpoint of an overarching loop joining the underlying active regions and a more distant one. These observations suggest that energy from the rearrangement of the magnetic field is being transferred, possibly by accelerated particles, along loops connecting widely-separated active regions on the Sun and that these conditions play a role in the triggering of energy release at coronal heights where decimetric noise storms occur.
Program listing for Tuesday