LARGE-SCALE CORONAL STRUCTURES IN EUV AND SOFT X-RAYS IN SOLAR CYCLE 23

摘要

We have analyzed the EIT/SOHO data in four EUV lines (171A, 195A, 284A and 304A) and soft X-ray YOHKOH data in two filters (AlMg and Al) in the form of coronal synoptic maps for the period 1996-2001 yrs. Two types of the bright structures have been detected in EUV in the axisymmetrically averaged synoptic maps. The structures of the first type migrate equatorward as the solar cycle progresses. They are related to complexes of sunspot activity and display the "butterfly"-type distribution. The structures of the second type migrate polarward and are associated with footpoints of giant coronal loops, which connect the polar regions and the following parts of the active complexes. These structures of coronal activity are also pronounced in the soft X-ray maps. However, the whole structure of the giant polar loops is visible in X-rays, and reveals connections to the low-latitude coronal structures. The relationship between the soft X-rays emission and the pho-tospheric magnetic flux obtained from SOHO/MDI and Kitt Peak Solar Observatory has been investigated. It has been found that the relationship depends on the phase of the solar cycle. We discuss the role of the magnetic flux in the formation and evolution of the stable coronal structures during the rising phase of cycle 23.