Abstract. On the agenda of modern astrophysics is the exploration of not only disk-integrated stellar magnetic fields but surface mapping of them. However, it is hardly possible to expect that spatial resolution better than some dozens or hundreds pixels over stellar disk will be achieved for this goal in the foreseeable future. Among other reasons this fact makes very important observations of the average and large-scale magnetic fields of the Sun, which can be naturally used for testing polarimetric measurements on other stars, especially on solar-type stars. In this study we explore different aspects of observations of solar magnetic fields (SMF) with low spatial resolution, including Sun-as-a-star observations, which are characterized by extremely low magnetic flux densities. Comparison of disk-integrated and spatially resolved Stokes observations of the Sun allow us to demonstrate how Stokes V profiles depend on the distribution of large-scale magnetic fields in the disk center. It is shown that center-to-limb variations of magnetic strength ratios (MSR) and area asymetries, most likely could be interpreted as the manifestation of kG magnetic flux tubes. We have made cross-calibration of the full-disk magnetograms obtained by space-borned SDO/HMI and by the ground-based STOP telescope, and pretty good agreement is found. Finally, the absence of significant systematic time variations of MSRs with solar cycle is demonstrated.
Abstract. The temperature, velocity and magnetic field structures of solar atmosphere are extremely in-homogeneous under consideration on a small spatial scales. This fact is the reason of significant difficulties in the attempts of disambiguous interpretation of observations. Particularly informative for investigation of the complex polarized radiation formation processes in the dynamic solar atmosphere with a fine-structured organization of magnetic fields are the distributions across the solar disk of the amplitude asymmetry (δa) and area asymmetry (δA) of Stokes profiles, as well as of the strength ratios R in different combinations of spectral lines. At this paper such information has been obtained using the Stokesmeter of the STOP telescope at the Sayan observatory. It was found that for some Fraunhofer lines the distribution of R has an evident equatorial-polar asymmetry, which is difficult to explain yet. Additionally this paper presents some new results of the theoretical simulation (with different parameters of magnetic flux tubes models and of the medium in their neighborhood) of the center-to-limb variations of δA on the example of the FeI λ525.02 nm spectral line and of the R = B 525.02/B524.70. The conclusion is made that a reasonably good agreement theory and experimental data can be achieved, for the time being, only for the central regions of the disk.
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