Results 1 - 10 of 1065
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[en] The relationship between disappearing solar fragments and geomagnetic disturbances was investigated. It is shown that long-delay storms are associated with filaments well removed from the disc centre, and particularly in the case of large filaments and prominences, the proportion of events that produce long-delay storms increases with angular distance from the centre
[en] Two large northern polar crown prominences that erupted on 2010 April 13 and 2010 August 1 were analyzed using images obtained from the Extreme UltraViolet Imager on the twin Solar Terrestrial Relations Observatory spacecraft. Several features along the prominence legs were reconstructed using a stereoscopic reconstruction technique developed by us. The three-dimensional changes exhibited by the prominences can be explained as an interplay between two different motions, namely helical twist in the prominence spine, and overall non-radial equatorward motion of the entire prominence structure. The sense of twist in both the prominences is determined from the changes in latitudes and longitudes of the reconstructed features. The prominences are observed starting from a few hours before the eruption. Increase in height before and during the eruption allowed us to study the kinematics of the prominences in the two phases of eruption, the slow-rise and the fast-eruptive phase. A constant value of acceleration was found for each reconstructed feature in each phase, but it showed a significant change from one leg to the other in both the prominences. The magnitude of acceleration during the eruptive phase is found to be commensurate with the net effect of the two motions stated above.
[en] Motions of loop prominence knots have been studied on Hα-line filtergrams. By making use of contours of equal photographic density for entire cinegram it has been possible to significantly decrease the error in determining the locations of the knots. The method of mean velocities has been developed, which has permitted for the first time accurate determination of the laws of knot motion with sufficient accuracy. Two types of falling knots are distinguished: (1) those with a constant acceleration that is always below the gravitational acceleration, and (2) those with a constant velocity. The initial velocity of the falling knots is always different from zero. The gasdynamic theory has been developed to explain the deceleration of the two types of knots due to: the work done against the pressure force; pileup plasma raking; and shock-wave generation. The shock mechanism imparts a constant velocity to the motion. The temperature along the knot trajectories has been estimated. The ratio of the densities in the knots to the surrounding medium has been found. The aim of the present work is to gain new insight into the known observations of the motions in active prominences, in particular in the loop prominences, and to understand the reason for the observed motions. (orig.)
[en] A statistical investigation was made of the height of prominences observed at Lomnicky Stit coronal station throughout the years 1967 to 1986. It was shown that the prominence height law distribution depended on the phase of the solar activity cycle. The height of polar prominences during cycle changed more than that of the prominences in the main zone. (author). 4 figs., 6 tabs., 24 refs
[en] The paper deals with the problem of a chromosphere spicule formation. By means of MHD equations and basing on a configuration of the magnetic field proposed in the paper, a number of spicules per supergranule is estimated and the dependence of this number on a height of a level of the spicule formation and on latitude is obtained. (author). 4 refs.; 2 figs
[en] The Glossary is designed to be a technical dictionary that will provide solar workers of various specialties, students, other astronomers and theoreticians with concise information on the nature and the properties of phenomena of solar and solar-terrestrial physics. Each term, or group of related terms, is given a concise phenomenological and quantitative description, including the relationship to other phenomena and an interpretation in terms of physical processes. The references are intended to lead the non-specialist reader into the literature. This section deals with: prominence; prominence classification and phenomenology; quiescent prominence; prominence zones; activated prominences; ascending (eruptive) prominence; ejections; surge; spray; and loop prominences. (B.R.H.)
[en] We present high spatial and temporal resolution Ca II 8542 A observations of a kink wave in an on-disk chromospheric active region fibril. The properties of the wave are similar to those observed in off-limb spicules. From the observed phase and period of the wave we determine a lower limit for the field strength in the chromospheric active region fibril located at the edge of a sunspot to be a few hundred gauss. We find indications that the event was triggered by a small-scale reconnection event higher up in the atmosphere.
[en] Using a 16-mm film recorded at Sacramento Peak Observatory with a 15-inch coronagraph, we have studied motions of three solar prominences from the kinematic point of view. We applied three methods proposed earlier to three prominences of the film. A new method based on geometrical considerations is introduced. The results of all the four methods are compared and discussed. (orig./WB)