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The halo CME  observed with UVCS/SOHO on April 29, 1998

Ester Antonucci


On April 29, 1998 the Ultraviolet Coronagraph Spectrometer (UVCS) onboard SOHO has observed  a halo coronal mass ejection in the HI Lyman alpha line (1216 A). The coronal mass ejection material crossed the coronagraph field of view, centered at position angle 144 degrees, counterclockwise  from the North pole,     (54S at the East limb) in the time interval  between 20.45 UT on April 29 and 04.22 UT on April 30, 1998. In this interval  the instantaneous   field of view moved from 1.7 to 3.6 solar radii. The Lyman alpha line profiles emitted by the coronal mass ejection plasma are  complex and extremely variable along the instantaneous field of view.  Doppler shifts are observed that indicate that the material velocity has a component in the direction of the observer of the order of 400 km/sec.

    Authors: E. Antonucci and C. Benna

  Organization: Osservatorio Astronomico di Torino
     Telephone:  39 011 8101913
           Fax:  39 011 8101930
        e-mail: antonucci@to.astro.it
       Address: Via Osservatorio 20
   Pino Torinese 10025

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