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In order to study the solar corona during eclipses, a new telescope was constructed. Three coronal images were obtained simultaneously through a single objective of the telescope as the coronal radiation passed through three polarizers (whose transmission directions were turned 0°, 60°, and 120°in the chosen direction); one image was obtained without a polarizer. The telescope was used to observe the solar corona during the eclipse of 1 August 2008. We obtained the distributions of polarization brightness, K-corona brightness, the degree of K-corona polarization and the total polarization degree; the polarization direction, depending on the latitude and radius in the plane of the sky, was also obtained. We calculated the radial distributions of electron density depending on the latitude. The properties of all these distributions were compared for different coronal structures. We determined the temperature of the coronal plasma in different coronal structures assuming hydrostatic equilibrium.

A solar eruptive event SOL2010-06-13 observed with the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO) has been extensively discussed in the contexts of the CME development and an associated extremeultraviolet (EUV) wave-like transient in terms of a shock driven by the apparent CME rim. Continuing the analysis of this event, we have revealed an erupting flux rope, studied its properties, and detected wave signatures inside the developing CME. These findings have allowed us to establish new features in the genesis of the CME and associated EUV wave and to reconcile all of the episodes into a single causally-related sequence. (1) A hot 11 MK flux rope developed from the structures initially associated with a compact filament system. The flux rope expanded with an acceleration of up to 3 km s −2 one minute before a hard X-ray burst and earlier than any other structures, reached a velocity of 420 km s −1 , and then decelerated to about 50 km s −1 .(2) The CME development was driven by the expanding flux rope. Closed coronal structures above the rope got sequentially involved in the expansion from below upwards, came closer together, and apparently disappeared to reveal their common envelope, the visible rim, which became the outer boundary of the cavity. The rim was probably associated with the separatrix surface of a magnetic domain, which contained the pre-eruptive filament.(3) The rim formation was associated with a successive compression of the upper active-region structures into the CME frontal structure (FS). When the rim was formed, it resembled a piston. (4) The disturbance responsible for the consecutive CME formation episodes was excited by the flux rope inside the rim, and then propagated outward. EUV structures arranged at different heights started to accelerate, when their trajectories in the distance-time diagram were SOLA: 2010-06-13_prep.tex; 15 March 2018; 2:25; p. 1 Grechnev et al. crossed by that of the fast front of this disturbance. (5) Outside the rim and FS, the disturbance propagated like a blast wave, manifesting in a type II radio burst and a leading part of the EUV transient. Its main, trailing part was the FS, which consisted of swept-up 2 MK coronal loops enveloping the expanding rim. The wave decelerated and decayed into a weak disturbance soon afterwards, being not driven by the trailing piston, which slowed down.Eruptive filament as a driver of a CME conditions. The authors concluded that its outer, propagating component had properties of a fast-mode wave, but their analysis could not ascertain the wave excitation scenario. It is still unclear where and how the presumable shock wave developed.Genesis of the flux rope, CME formation, and shock wave excitation scenario are common long-standing issues for many similar events. Addressing these issues promises reconciliation of existing concepts with observational challenges and progress in understanding eruptive events and underlying processes.The basic guidelines to solve these problems are provided by the ...

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