Abnormal Stokes profiles of the photospheric lines in the region of chromospheric dual flows in the surroundings of a solar pore. II. Photospheric models

Heading: 
1Kondrashova, NN
1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2018, 34(4):30-52
Start Page: Solar Physics
Language: Russian
Abstract: 

The thermodynamic parameters and parameters of the photospheric magnetic field in the region of chromospheric dual flows in the vicinity of a small pore in the active region NOAA 11024 are presented. Dual chromospheric flows have appeared in the region of anomalous Stokes V profiles of the photospheric lines and were associated with the emergence of a new small-scale magnetic flux of positive polarity. Semi-empirical photospheric models were obtained by inversion using the SIR program (Stokes Inversion based on Response functions) [Ruiz Cobo, del Toro Iniesta. Astrophys. J. 1992. 398. P. 375]. Each model contains two components: two thin magnetic flux tubes of different polarity. In the first component, the magnetic flux has a negative polarity, in the second component it is positive. Stokes profiles of the photospheric lines Fe I λ 630.15, 630.25 nm, 630.35 nm and Ti I λ 630.38 nm from spectropolarimetric observations with the French-Italian telescope THEMIS (Tenerife, Spain) were used for modeling. The height dependences of the temperature, the line-of-sight velocity, the angle of inclination of the magnetic field vector and the azimuth angle in the tubes, as well as the values of the magnetic field strength and the macroturbulent velocity are obtained. Time variations in all parameters of the photosphere are revealed. The new magnetic flux emerged in the region of mixed polarities and was accompanied by the warming of the photosphere and the chromosphere. The inferred flux tube models show the temperature enhancement up to 400 K in the upper photospheric layers relative to the quiet-Sun model temperature. They indicate a complex, inhomogeneous small-scale structure of the magnetic field and the velocity field. The magnetic field strength in the tubes varies from 0.03 to 0.13 T during the period under consideration. The angles of the inclination of the magnetic field vector and the azimuth angles strongly differ in magnetic flux tubes and vary in time. The line-of-sight velocity does not exceed 2 km/s. The downflows in the lower layers of the photosphere and the upflows in the upper layers are dominated in the first component of the models. In the second component of the model, the material is lifted in the upper photosphere. The macroturbulent velocity in most cases exceeds its value for the unperturbed photosphere. The velocity is greater in the second component of the models. The emergence of the new magnetic flux could lead to the magnetic reconnection and occurrence of a microflare.

Keywords: active regions, magnetic fields, photosphere, spectropolarimetry, the Sun
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