Radio Detection of a Rapid Disturbance Launched by a

We report the direct observation of motion associated with a solar are at a speed of 26000 km s ?1. The motion is seen from a radio source at 0.33 GHz, which suddenly starts moving during the are. At its peak the radio source covers a quiet region of dimension 500 00. Emission from any given location is sporadic. The disturbance itself does not seem to radiate, but it excites coronal features which continue to radiate after it passes. The inferred velocity is larger than any previously inferred velocity of a disturbance in the solar atmosphere apart from freely{streaming beams of accelerated electrons. The observed motion of the source at a xed frequency, low polarization and moderate bandwidth are more consistent with the typical properties of moving Type IV radio bursts than with classical coronal{shock{associated Type II bursts, but any disturbance at such a high velocity must be highly supersonic and should drive a shock. We speculate that the disturbance is associated with the realignment of magnetic elds connecting diierent portions of an active region.