Signatures of quiet Sun reconnection events in Ca~{\sc ii}, H$\alpha$ and Fe~{\sc i}

Abstract

We use observations of quiet Sun (QS) regions in the H$\alpha$ 6563 Å, Ca~{\sc ii} 8542 Å\, and Fe~{\sc i} 6302 Å lines. We observe brightenings in the wings of the H$\alpha$ and Ca~{\sc ii} combined with observations of the interacting magnetic concentrations observed in the Stokes signals of Fe~{\sc i}. These brightenings are similar to Ellerman bombs (EBs), i.e. impulsive bursts in the wings of the Balmer lines which leave the line cores unaffected. Such enhancements suggest that these events have similar formation mechanisms to the classical EBs found in active regions, with the reduced intensity enhancements found in the QS regions due to a weaker feeding magnetic flux. The observations also show that the quiet Sun Ellerman bombs (QSEBs) are formed at a higher height in the upper photosphere than the photospheric continuum level. Using simulations, we investigate the formation mechanism associated with the events and suggest that these events are driven by the interaction of magnetic field-lines in the upper photospheric regions. The results of the simulation are in agreement with observations when comparing the light-curves, and in most cases we found that the peak in the Ca~{\sc ii} 8542 Å wing occurred before the peak in H$\alpha$ wing. Moreover, in some cases, the line profiles observed in Ca~{\sc ii} are asymmetrical with a raised core profile. The source of heating in these events is shown by the MURaM simulations and is suggested to occur 430 km above the photosphere.

14 pages, 11 figures, 1 table (Published on 2018/6/1)

References in corpus (10)

• CRISP Spectropolarimetric Imaging of Penumbral Fine Structure
• Hot Explosions in the Cool Atmosphere of the Sun
• Bombs and flares at the surface and lower atmosphere of the Sun
• Small-Scale Structuring Of Ellerman Bombs at Solar Limb
• Simulating Ellerman bomb-like event
• Large-Amplitude Oscillation of an Erupting Filament as Seen in EUV, H-alpha and Microwave Observations
• IRIS Burst Spectra Co-Spatial To A Quiet-Sun Ellerman-Like Brightening
• Statistical Analysis of Small Ellerman Bomb Events
• Ellerman Bombs with Jets: Cause and Effect
• Chromospheric Inversions of a Micro-flaring Region

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• Properties of ubiquitous magnetic reconnection events in the lower solar atmosphere
• Transient brightenings in the quiet Sun detected by ALMA at 3 mm
• Signatures of ubiquitous magnetic reconnection in the deep atmosphere of sunspot penumbrae
• A reconnection driven magnetic flux cancellation and a quiet Sun Ellerman bomb
• Quiet Sun Ellerman bombs as a possible proxy for reconnection-driven spicules
• Spectroscopic Case Studies of Four Long-duration Transition-region Explosive Events
• Small-scale energetic phenomena in Hε: Ellerman bombs, UV bursts, and small flares