Roman I. Kostik

The results of spectropolarimetric and filter observations of a faculae region located near the solar disc center in the Fe I 1564.3, Fe I 1565.8, Ba II 45

The results of spectropolarimetric and filter observations of the facular region in the lines Fe I 1564.3, Fe I 1565.8 nm, Ba II 455.4 nm, and Ca

The observations of the solar facula in the Ba II λ 455.403 Å line are used to construct a 3D model of the facula area by solving the invers

The validity of the lambda-meter method for determining the quiet Sun velocity field using the Si I 1082.7 nm line is investigated. To this end, the intens

According to the data of complex 2D observations on the VTT telescope of the solar facula, a 3D model of the solar atmosphere in the facular region was obt

The results of the observations of the active region (facula) near the center of the solar disk obtained with the German Vacuum Tower Telescope (VTT; Tenerife, Spain), are discussed. We have...

Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics

This paper studies the dependence of the CaIIH line core brightness on the strength and inclination of photospheric magnetic field, and on the parameters of convective and wave motions in a facular region at the solar disc center. We use three simultaneous datasets obtained at the German Vacuum Tower Telescope (Observatorio del Teide, Tenerife): (1) spectra of BaII 4554 A line registered with the instrument TESOS to measure the variations of intensity and velocity through the photosphere up to the temperature minimum; (2) spectropolarimetric data in FeI 1.56 $\mu$m lines (registered with the instrument TIP II) to measure photospheric magnetic fields; (3) filtergrams in CaIIH that give information about brightness fluctuations in the chromosphere. The results show that the CaIIH brightness in the facula strongly depends on the power of waves with periods in the 5-min range, that propagate upwards, and also on the phase shift between velocity oscillations at the bottom photosphere and around the temperature minimum height, measured from BaII line. The CaIIH brightness is maximum at locations where the phase shift between temperature and velocity oscillations lies within 0-100 degrees. There is an indirect influence of convective motions on the CaIIH brightness. Namely, the higher is the amplitude of convective velocities and the larger is the height where they change their direction of motion, the brighter is the facula. Altogether, our results lead to conclusions that facular regions appear bright not only because of the Wilson depression in magnetic structures, but also due to real heating.

Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics