UV line intensity and flow velocity distributions in two coronal mass ejections as deduced by UVCS-SOHO observations
Osservatorio Astrofisico, Città Universitaria, Via S. Sofia 78, 95125 Catania, Italy
2 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
Corresponding author: R. Ventura, firstname.lastname@example.org
Accepted: 14 December 2001
The Ultraviolet Coronagraph Spectrometer (UVCS) instrument onboard the SOHO satellite observed two coronal mass ejections on November 2 and 3, 2000, related to the eruptions of a large filament structure in an active region close to the West limb of the Sun, and of a prominence near the South Pole, respectively. Intensity and profile of the O VI resonance doublet lines at 1032 and 1037 Å and of Lyβ (1026 Å) line, together with the intensity of some other minor ions, were observed using the O VI channel of UVCS. We analysed these spectroscopic observations in order to get information about the distributions of ionic densities and flow velocities in the solar coronal plasma ejected during these transient events. Emission in ions ranging from C II to O VI indicates a temperature range between 104.5 and 105.5 K. The morphology of the bright emission regions suggests the development of several strands of plasma irregularly distributed inside the CME structures, whose temporal evolution is significantly different from each other. The velocities determined for each bright element also give a complex picture of the plasma kinematics characterizing these coronal mass ejections.
Key words: Sun: corona / Sun: UV radiation
© ESO, 2002