Abstract:

In this paper, we review our latest studies on a newly-discovered phenomenon dubbed “streamer waves” which are excited in the aftermath of CME-streamer interaction. Streamer waves represent one of the largest wave phenomena ever observed in the solar corona. The wave mode is interpreted as the fast kink body mode supported by and propagating outwards along the plasma sheet of the streamer. With the white light coronagraph data and available observational constraints on the solar wind parameters, we develop a novel seimological technique to diagnose the radial profiles of the Alfv?n speed and magnetic field strength in the region surrouding the plasma sheet structure from 3 to 10 solar radii. We also conduct a data survey searching for welldefined streamer wave events observed by the SOHO／LASCO coronagraph throughout Solar Cycle 23. As a result, eight candidate events are found. We compare different events and find that in most of them the driving CMEs’ ejecta are characterized by a high speed and a wide angular span, and the CMEstreamer interactions occur generally along the flank of the streamer structure at an altitude no higher than the bottom of the field of view of LASCO C2. In addition, all front-side CMEs have accompanying flares. These common observational features shed light on the excitation conditions of streamer wave events.

Key words:  corona, coronal mass ejections, streamer waves, coronal seismology