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Information × Registration Number 0219U102023, 0119U103753 , R & D reports Title Optical observations of the Sun and modeling of wave processes in the solar atmosphere popup.stage_title Head Shchukina Nataliya G., д.ф.-м.н. Registration Date 13-12-2019 Organization Main Astronomical Observatory popup.description2 Observations of the line intensity profile variations during the extreme minimum of the current 24th cycle of the solar activity (so called spotless period in August-September 2019) were performed with high spectral and temporal resolution using Ernest Gurtovenko telescope of the Main Astronomical Observatory of the NAS of Ukraine. Thermodynamic parameters of the solar atmosphere were recovered by means of inversion of the observed line profiles. It is found that the central depth, equivalent width, half-width and bisector deflection of the spectral lines, which are formed in the quiet regions of the solar atmosphere, correlate with the magnetic activity indices of the Sun. For the first time it was discovered that in the minimum of the 11-year solar cycle the low photosphere is getting cooler and the middle photosphere on the contrary becomes hotter. The properties of the acoustic wave propagation from the lower photosphere to the chromosphere were analyzed using magneto-hydrodynamic models of the solar atmosphere. In particular, it was considered the dependence of the amplitudes of the line intensity oscillations and the velocity oscillations on the magnetic field strength as well as phase shift between velocity and temperature oscillations at different heights in the solar atmosphere. Results of modeling were compared with spectral, filter and spectropolarimetric observations obtained on the vacuum telescope VTT (Instituto de Astrofísica de Canarias, Spain). For the first time it was shown that solar plages are bright with respect to the surrounding matter, not only because of the Wilson effect, but also because the plasma temperature is indeed higher than the surrounding non-magnetic environment.   Product Description popup.authors Kostik Roman I. Osipov Sergiy M. Pishkalo Mykola I. Shukina Nataliya G. popup.nrat_date 2020-04-02 Close