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Session 1 - Chromosphere, Corona, Flares.
Display session, Friday, June 27
Ballroom B, Chair: Charles Kankelborg

[1.21] Ultraviolet Spectroscopy of Coronal Mass Ejection

A. Ciaravella (European Space Agency and Smithsonian Astrophysical Observatory), J. C. Raymond (Harvard-Smithsonian Center for Astrophysics), S. Fineschi (Smithsonian Astrophisical Observatory), M. Romoli (University of Florence - Italy), E. Antonucci (University of Torino - Italy)

The Ultraviolet Coronagraph Spectrometer (UVCS) observed a spectacular coronal mass ejection (CME) on December 23 1996, caused by a prominence eruption. The evolution of the ejected plasma was followed for about 2h in both ultraviolet and visible light channels. The observation consists of a series of 5 minutes exposures, at heliocentric distance of 1.5 R_ødot. Excursions of more than two orders of magnitude are detected in the Ly\alpha (1216 Å\/), Ly\beta (1026 Å\/), Ly\gamma (972 Å\/) and Ly\delta (949 Å\/) lines of hydrogen. The C III (977 A) is very bright during the CME evolution, but many other more weak low temperature lines, like N III (991 Å\/, 991 Å\/), N II (1085 Å\/), N V (1242 Å\/), have been detected. Line intensities and profiles have been measured providing important diagnostics for a very detailed study of physical and dynamical parameters of CME. Lines widths show non-thermal line broadening due to an expansion of plasma with velocity larger than 50 km/sec. The Ly\alpha spatial pattern of the line shift appears very structured with red and blue shifts, along the line of sight, up to 0.2 Å\/ ( 50km/sec) and 1 Åkm/sec) respectively. The data also provide the emission measure in the LogT range 4.0 - 5.5. A variation of one order of magnitude has been observed in the polarized brightness.


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