Morphology Of Ellerman Bursts

Ellerman Bursts (EBs) sporadically appear in the form of compact brightenings in the H-alpha line wings near solar active regions, and their enigmatic spectral property was mainly studied for the diagnostics on the heated atmosphere. Morphological property of EBs was much less attended because they appear to be structureless in the scale of 1-2 arcsec. We present EB’s spatial morphology and temporal evolution of magnetic fields around EBs, utilizing high-resolution H-alpha images from the Visible Imaging Spectrometer (VIS) and magnetograms from the Near-InfraRed Imaging Spectropolarimeter (NIRIS) of the 1.6 m Goode Solar Telescope (GST) at Big Bear Solar Observatory. These two instruments provide image scales of 0.034 arcsec and 0.083 arcsec per pixel respectively, along with spectral information in the wavelength interval of 0.2 A in the H-alpha line. UV images from the Solar Dynamic Observatory (SDO) are used for cross checking the energy release at the site of EBs. Main result of this study is that EBs indeed have sub-arcsec scale structures, which we classify into four different types: flame-like, sheet-like, crown-like, and simple round morphologies. We discuss how these EB morphologies result and what makes EBs distinct from a small version of flares based on the fine-scale ambient magnetic field configuration and evolution.