Spectral study of pair Ellerman bombs

1Pasechnik, MN
1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
Kinemat. fiz. nebesnyh tel (Online) 2016, 32(2):3-24
Start Page: Solar Physics
Language: Russian

The results of the spectral observation analysis in the Hα line of two Ellerman bombs (EB-1 and EB-2), which were formed and have developed in the active region NOAA 11024 in the emerging magnetic flux area, are presented. The spectral data, with high temporal and spatial resolution, were obtained with the French-Italian solar telescope THEMIS (the island of Tenerife, Spain) on July 4, 2009. The Hα line profiles, obtained during different periods of the EBs evolution, were asymmetrical with excess emission in the long-wavelength wing. The intensity changes of the line wings indicate that the EBs occurred as a gradual and pulsed release of energy. The temporal variations of the chromospheric line-of-sight velocities (Vlos ) at the heights of the Hα core formation meant that there were two periods of increasing the Vlos consisting of several individual peaks. The maximum Vlos toward and from the observer was –9 km/s and 8 km/s, respectively. During observation there were some moments of upward plasma flows with Vlos up to –80 km/s and downward flows with Vlos up to 50 km/s. Ellerman bombs were accompanied by small chromospheric ejections (surges), lasting about 0.5 — 1.5 minutes. The fine structure of EB found on the Hα line spectra, was obtained during the sharp increase of intensity in the Hα line wings lasting about 4 minutes. Features of intensity change in the line wings and variations of the line-of-sight velocity of chromospheric matter indicate that the two investigated EBs occurred and developed as a physically connected pair. Our results support a model in which the triggering mechanism of formation EBs is a magnetic reconnection in the lower atmosphere.

Keywords: Ellerman bombs, line-of-sight velocities, the Sun

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