Hot coronal plasma phenomena seen by the CORONAS missions
Dr A.M. Urnov - P.N. Lebedev Physical Institute of RAS, Russia
July 08, 2010, 14:30u, Meridian
The advent of XUV full-Sun monochromatic imaging spectroscopy in the SPIRIT experiment on CORONAS-F (2001-2005)
helped to reveal highly dynamic 4 - 20 MK coronal plasma structures characterized by various sizes from 6"
through 0.3 solar radius and lifetimes from several minutes to several days. A new phenomenon of hot spots
(hot X-ray bright points, HXBP) has been disclosed in addition to the previously reported giant post-eruptive
sources (spiders). The whole Sun X-ray emission (GOES) was shown to be the result of a superposition of a
series of low intensity elemental bursts lasting for 10-20 min and recurring at the same locations on
the solar disk. These events were classified as impulsive events (IE) and gradual ones (GE) implying
different mechanisms of formation and decay. A new concept based on a quasi-static model was proposed to
explain the observable features of gradual events. It was used to provide a theoretical description of the
spider phenomena using generalized Chandrasekhar-Prendergast model of a spherical magnetic vortex. This model
reveals remarkable properties that help to explain how the conditions sufficient for fast and efficient
energy release, specific for a weak flare, may take place sporadically without disrupting the whole system.
The results of observations of highly dynamical coronal structures by CORONAS-PHOTON mission (2009-2010)
will be also presented.
