Composition of Coronal Streamers from the SOHO Ultraviolet Coronagraph Spectrometer
Romoli, M.; Raymond, J. C.; Naletto, G.; Modigliani, A.; Poletto, G.; Ciaravella, A.; Fineschi, S.; Benna, C.; Giordano, S.; Michels, J.; Antonucci, E.; Noci, G.; Nicolosi, P.; Spadaro, D.; Huber, M. C. E.; Strachan, L.; Kohl, J. L.; Tondello, G.; Gardner, L. D.; Siegmund, O. H. W.; Karovska, M.; Martin, R.; Pernechele, C.; Suleiman, R. M.; Panasyuk, A.; Cranmer, S.; Smith, Peter L.
United States, Italy, Netherlands, Switzerland, France
Abstract
The Ultraviolet Coronagraph Spectrometer on the SOHO satellite covers the 940-1350 Å range as well as the 470-630 Å range in second order. It has detected coronal emission lines of H, N, O, Mg, Al, Si, S, Ar, Ca, Fe, and Ni, particularly in coronal streamers. Resonance scattering of emission lines from the solar disk dominates the intensities of a few lines, but electron collisional excitation produces most of the lines observed. Resonance, intercombination and forbidden lines are seen, and their relative line intensities are diagnostics for the ionization state and elemental abundances of the coronal gas.