Surges as tracers of magnetic lines

During the maximum activity year 1980, chromospheric mass ejections were observed with the Multichannel Subtractive Double Pass Spectrograph operating at Meudon (MSDP), while the UV and X-ray emissions were observed respectively with Ultra Violet Spectrograph (UVSP) and HXIS instruments on board the SMM (Solar Maximum Mission) satellite. These ejections are not related directly to flares but are located in active regions near sunspots. As the magnetic field is frozen in the matter, the study of the velocity field leads to the geometry of the magnetic structures and to the temporal evolution of the magnetic field lines. Ejections of matter recur often with a period of 10 to 20 minutes. In CIV, the bright loops coincide with the Hα surge but are more extended. Associated with the events are either X-ray emission or type III bursts. These signatures are interpreted by invoking, respectively, closed or open structures. The estimate of the energy involved gives constraints on the mechanism responsible for the surge. (author). 7 figs., 14 refs