CME-associated dimmings on the Sun observed with the EUV SPIRIT telescope on the CORONAS-F spacecraft Original Research Article

Based on observations with the EUV SPIRIT telescope aboard the CORONAS-F spacecraft, we analyze large-scale dimmings on the solar disk initiated by halo-type coronal mass ejections (CMEs). We address four powerful geo-effective eruptive events of November 4, 2001; October 28, 29, and November 18, 2003. The SOHO/EIT telescope did not observe the first event. Considering other events, we demonstrate that the CORONAS-F/SPIRIT and SOHO/EIT data well supplement each other in time and spectral coverage. The spatial coincidence of the main dimmings in different-temperature lines hints at their relation to plasma outflow from partly or completely opened magnetic structures in the transition region and corona. For some dimmings whose appearance is dissimilar in different lines, CME-associated variations of the plasma temperature can play a role as well. Peculiar propagating darkening was detected in the SPIRIT 304 Å band on November 18 between 08:23 and 09:54 UT. Most probably, the darkening is caused by some absorption of the emission in cold material of the erupted filament.