We study the coronal mass ejection (CME) with a complex acceleration profile. The event occurred on April 23, 2009. It had an impulsive acceleration phase, an impulsive deceleration phase, and a second impulsive acceleration phase. During its evolution, the CME showed signatures of different acceleration mechanisms: kink instability, prominence drainage, flare reconnection, and a CME-CME collision. The special feature of the observations is the usage of the TESIS EUV telescope. The instrument could image the solar corona in the Fe 171Å line up to a distance of 2 R ⊙ from the center of the Sun. This allows us to trace the CME up to the LASCO/C2 field of view without losing the CME from sight. The onset of the CME was caused by kink instability. The mass drainage occurred after the kink instability. The mass drainage played only an auxiliary role: it decreased the CME mass, which helped to accelerate the CME. The first impulsive acceleration phase was caused by the flare reconnection. We observed the two ribbon flare and an increase of the soft X-ray flux during the first impulsive acceleration phase. The impulsive deceleration and the second impulsive acceleration phases were caused by the CME-CME collision. The studied event shows that CMEs are complex phenomena that cannot be explained with only one acceleration mechanism. We should seek a combination of different mechanisms that accelerate CMEs at different stages of their evolution.
High-resolution temporal series of monochromatic full-Sun images in the L Mg XII emission line at 8.42Å have been obtained by the SPectroheliographIc X-Ray Imaging Telescope (SPIRIT) spectroheliograph on the CORONAS-F satellite. For a six-month period since the launch on 2001 July 31 more than 10 000 Mg XII images were recorded. The images revealed plasma structures with the temperature in the range 3-20 MK characterized by specific shape and dynamics, different to that of relatively low temperature (1-2 MK) plasma. The main remarkable features of the phenomena first seen in the monochromatic images are as follows:(1) high spatial variability in brightness with the contrast of more than two orders of magnitude, (2) the presence of some compact sources with high altitude locations up to 0.3 solar radius and well-distinguished 'spider'-like forms, (3) substantially different variability in dynamical behaviour characterized by lifetimes from minutes to days. Sporadic condensations of coronal plasma with log N e ≈ 10 and peak temperature of about 10 MK were observed in the vicinity of active region systems.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.