Oxygen Abundance Variations in Coronal Streamers Affected by CMEs

VÁSQUEZ, ALBERTO M.; RAYMOND, JOHN C.

Giardini Naxos, Sicilia, Italia.

Conferencia; SOHO-17. 10 Years of SOHO and Beyond; 2006

European Space Agency

We present a study on the variation of the oxygen abundance within equatorial streamers affected by coronal mass ejections (CMEs). We select CME events during the period of minimum solar activity May 1996 - March 1997, from the Large Angle Spectroscopic Coronagraph (LASCO/SoHO) CME catalog. The selected events have diverse intensities and affect the coronal streamer belt structure. For each event, we derive the oxygen abundance within the streamer belt from spectroscopic coronal observations performed with the Ultraviolet Coronagraph Spectrometer (UVCS/SoHO). We analyze UVCS data obtained before and after the actual CME occurrences. Within the streamer belt core structure the oxygen abundance usually exhibits a depleted region, presumably due to gravitational settling. We analyze how this degree of depletion changes within streamers observed before and after CME events of diverse intensities. We report our main results and discuss their implications for the dynamics of the streamer region.