Dynamic 10 MK plasma structures observed in monochromatic full-Sun images by the SPIRIT spectroheliograph on the CORONAS-F mission

Abstract

High-resolution temporal series of monochromatic full-Sun images in the L Mg xii emission line at 8.42 Å 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 Ne≈ 10 and peak temperature of about 10 MK were observed in the vicinity of active region systems.