Motion of the photospheric matter in the active region site with two Ellerman bombs

Heading: 
Solar Physics
1Pasechnik, MN
1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2019, 35(2):3-27
https://doi.org/10.15407/kfnt2019.02.003
Start Page: Solar Physics
Language: Russian
Abstract: 

The results of the feature changes analysis of the line-of-sight velocities plasma in different layers of the photosphere of the active region NOAA 11024 under the action appeareing and developing two Ellerman bombs (EB-1 and EB-2) are presented. Spectral data with high spatial and temporal resolution (about 3 seconds) were obtained with the French- Italian solar telescope THEMIS on July 4, 2009. The observation time was 20 minutes. On the day of the observations, the AR was at the stage of a sharp increase in activity and the Ellerman bombs developed in the region of one of the three magnetic fluxes that were emerging at this time. The brightness of EB-1 decreased in the process of observations, while the brightness of EB-2 increased. We used a spectral region of ≈ 630 nm, which included four Fraunhofer lines that are formed over a wide range of photospheric heights: the neutral iron lines Fe I 630.15 nm, 630.25 nm, 630.35 nm and the titanium line Ti I 630.38 nm. Changes in the velocity and direction of motion of matter in the areas of Ellerman bombs and in their immediate vicinity at different levels of the photosphere and at different stages of EBs development are determined and analyzed. Studies have shown that at all levels of the AR photosphere predominantly upflows were observed. At the same time, a noticeable decrease of the line-of-sight velocity magnitudes and the amplitude of their oscillations was observed at the location of the EBs. This indicates that small-scale downward movements were superimposed on the large-scale upward motion of the plasma new magnetic flux. This conclusion is confirmed by the shape of photospheric line profiles. The profiles of strong lines had a red asymmetry. The velocity of the matter, determined by the component displacement, which stood out well in the red wing of the Fe I 630.35 nm line profiles, reached 2 km/s. Such a distribution of in the EB regions indicates that they consisted of several jets moving at different velocities and in different directions. In the central part of the EB-1 and EB-2 in the upper layer of the photosphere, the line-of-sight velocity varied between –1...0 km/s and –1...0.2 km/s, in the lower layer of the photosphere — between –1.6...–0.2 km/s and –1.1...0.25 km/s, respectively. In the vicinities of the Ellerman bombs, the variations of were oscillatory, the interval between oscillations was about 5 minutes. In the EB regions, the picture of quasiperiodic oscillations of the was disturbed, in many cases they occurred in antiphase. Based on the research, it can be concluded that the excitation caused by pulsed energy release as a result of successive magnetic reconnections associated with the release of a new magnetic flux propagated from the EB-1 area along the magnetic loop and initiated the formation of EB-2, then they developed as physically connected pair. The studied features of the temporal changes in the line-of-sight velocity of the chromospheric and photospheric matter in the Ellerman bomb regions and their vicinity indicate that during the development of EBs, multidirectional movement was observed — in the lower chromospheric layer the matter moved upward, and also streams formed that moved downward, reducing the velocities of the ascending plasma at the photospheric level. Such a distribution of velocities could cause magnetic reconnections that occurred in the layer between the upper photosphere and the lower chromosphere, where the core of the Нα line was formed.
Keywords: Ellerman bombs, line-of-sight velocities, photosphere, spectral research, Sun

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