Abstracts submitted by Vladimir Slemzin
Off-limb EUV observations of the diffuse and structured solar corona and transient phenomena at 1-5 Rsun with the CORONAS-F/SPIRIT telescope-coronagraph
V. Slemzin[1], O. Bougaenko [2], A. Ignatiev [1], S. Kuzin [1], A. Mitrofanov [1], A. Pertsov [1], I. Zhitnik [1]
[1] P.N. Lebedev Physical Institute, Moscow, Russia; [2]Sternberg Astronomical Institute, Moscow State University, Moscow, Russia
During the flight of the CORONAS-F satellite (August 2001- December 2005), the SPIRIT telescope observed the solar corona in 175 and 304 Å bands in the off-limb coronagraphic mode. In this mode the central part of the aperture was closed by the external occulter and the focusing mirrors were tilted to observe the selected sector of the solar corona at the distance of 1.1-5 Rsun from the Sun center with spatial resolution of 5". This range is intermediate between fields of view of EIT (0-1.3 Rsun), UVCS (1.5-12 Rsun), LASCO C2 (2-7 Rsun) and is very important for forming the streamer belt and emergence of slow solar wind. The images of the corona in 175 and 304 Å bands were taken simultaneously with 150 or 300 s exposure times and with enhanced sensitivity of the detector (in 25-53 times more than in the disk mode). Observations were made during the periods from 1 day to several weeks with a cadence of 0.5-1 h. In the 175 Å band corresponding to T~ 1 MK the corona at the solar maximum (2001-2002) consisted of diffuse part and a distinct system of quasi-radial diverging loops and rays observed to the distances up to 2-2.5 Rsun. Most of these features were not seen in the 304 Å band. Both components showed short-term (hours) and long-term (days) variations with the activity of underlying regions. In the coronagraphic mode we detected also several transient phenomena such as prominence eruptions and jets. We analyze the results and compare them with the corresponding data of EIT, UVCS, CDS and LASCO. |
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