H-ALPHA SURGES AND ASSOCIATED SOFT-X-RAY LOOPS

A recurrent H alpha surge was observed on 7 October, 1991 on the weste rn solar limb with the Meudon MSDP spectrograph. The GOES satellite re corded X-ray subflares coincident with all three events. During two of the surges high-resolution Yohkoh Soft X-ray Telescope (SXT) images h ave been taken. Low X-ray loops overlying the active region where the surges occurred were continuously restructuring. A flare loop appeared at the onset of each surge event and somewhat separated from the foot point of the surge. The loops are interpreted as causally related to t he surges. It is suggested that surges are due to magnetic reconnectio n between a twisted cool loop and open field lines. Cold plasma bubble s or jets squeezed among untwisting magnetic field lines could corresp ond to the surge material. No detection was made of either X-ray emiss ion along the path of the surges or X-ray jets, possibly because of th e finite detection threshold of the Yohkoh SXT.