Bulletin of Taras Shevchenko National University of Kyiv. Astronomy, no. 64, p. 5-12 (2021)

Study of the connection between Ellerman bomb and Hα-surges

M. Pasechnik, PhD

Main astronomical observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine


Based on the analysis of spectral observations in the H α line of a site of the active region NOAA 11024, where the Ellerman bomb appeared and developed and during our observations various types of chromospheric matter ejections were formed, a study of the connection between these small-scale elements of solar activity has been carried out. Spectral data with high spatial and temporal resolution were obtained with the French–Italian 90-cm vacuum telescope THEMIS (Tenerife, Spain) on July 4, 2009. The observation time was 20 minutes. The AR site under investigation was in the region of a new magnetic flux emerging at this time. A site with high activity was select – it was pore on it, the Ellerman bomb (EB) was developing and many chromospheric ejections (surge) arose. The features of the formation and development of surges that appeared near the pore, which was at a distance of 7.2 Mm from the Ellerman bomb, were studied. Changes in the line-of-sight velocity (Vlos) and the direction of chromospheric matter motion in Hα-surges are analyzed. During our observations, the maximum plasma velocity upward reached – 95 km/s, and downward – 80 km/s. In the upper part of the magnetic loops, the Vlos of the plasma varied between – 20 km/s and 15 km/s. The velocity values in the area without active formations did not exceed ± 2 km/s. The distribution of velocities within Hα-surges showed that they mainly had a fine structure – they consisted of several jets. In most cases, upward and downward plasma flows occurred simultaneously with an increase in the EB brightness. Our study showed that during a sharp increase in the brightness of the EB, the chromospheric mater velocities in the surges increased, the direction of its movement changed, new surges appeared, which indicates a connection of the Hα-surges that developed near the pore with the Ellerman bomb, as well indicates that all these processes were the result of magnetic reconnections caused by the emergence of a new serpentine magnetic flux and its interaction with the pre-existing magnetic field.

Key words
Active region, magnetic flux, magnetic reconnection, Ellerman bomb, H α-surge.

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DOI: https://doi.org/10.17721/BTSNUA.2021.64.5-12