Eruption of Prominences Triggered by Coronal Rain in the Solar Atmosphere Observed by SDO/AIA and Stereo/EUVI

The triggering process for coronal mass ejections (CME) in the solar atmosphere is not fully understood. We use observations from different spacecraft at several wavelengths to detect an instability process for a prominence/filament with subsequent eruption of CME. Time series of spectral lines at 304, 171, 193, and 211 Å have been obtained with the SDO spacecraft, and at 304, 171, 195, and 284 Å with the STEREO spacecraft. A prominence/filament system was observed during November 8-23, 2011, at different angles by SDO, STEREO_A, and STEREO_B. The observations show that a giant tornado began to develop near the base of the prominence at 20:00 UT on November 20, which later caused the appearance of droplets of coronal rain (at 16:00 UT, November 21) which fell downward from the main mass of the prominence. The coronal rain continued until 20:20 UT, November 22, and caused an instability of the prominence, after which a CME took place 22:30 UT on November 22. We assume that the loss of mass owing to coronal rain may lead to instability of prominences and their subsequent eruption. Observations of coronal rain falling from the main part of the mass of prominences could be used for predicting space weather.