Multi-wavelength Spectral Analysis of Ellerman Bombs Observed by FISS and IRIS

Abstract

Ellerman bombs (EBs) are a kind of solar activities that is suggested to occur in the lower atmosphere. Recent observations using the Interface Region Imaging Spectrograph (IRIS) show connections of EBs and IRIS bombs (IBs), implying that EBs might be heated to a much higher temperature ($8\times 10^4$ K) than previous results. Here we perform a spectral analysis of the EBs simultaneously observed by the Fast Imaging Solar Spectrograph (FISS) and IRIS. The observational results show clear evidence of heating in the lower atmosphere, indicated by the wing enhancement in H$\alpha$, Ca II 8542 Å and Mg II triplet lines, and also by brightenings in the images of 1700 Å and 2832 Å ultraviolet continuum channels. Additionally, the Mg II triplet line intensity is correlated with that of H$\alpha$ when the EB occurs, indicating the possibility to use the triplet as an alternative way to identify EBs. However, we do not find any signal in IRIS hotter lines (C II and Si IV). For further analysis, we employ a two-cloud model to fit the two chromospheric lines (H$\alpha$ and Ca II 8542 Å) simultaneously, and obtain a temperature enhancement of 2300 K for a strong EB. This temperature is among the highest of previous modeling results while still insufficient to produce IB signatures at ultraviolet wavelengths.

19 pages, 8 figures, accepted by ApJ

References in corpus (6)

• Hot Explosions in the Cool Atmosphere of the Sun
• Spectral observations of Ellerman bombs and fitting with a two-cloud model
• Small-Scale Structuring Of Ellerman Bombs at Solar Limb
• Observations and NLTE modeling of Ellerman bombs
• Observations of Ellerman bomb emission features in He I D3 and He I 10830 Å
• Ellerman Bombs with Jets: Cause and Effect

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• RADYN simulations of non-thermal and thermal models of Ellerman bombs
• Solar surges related to UV bursts: Characterization through k-means, inversions and density diagnostics
• Chromospheric and coronal heating and jet acceleration due to reconnection driven by flux cancellation. II. Cancellation of two magnetic polarities of unequal flux
• The Ellerman bomb and Ultraviolet burst triggered successively by an emerging magnetic flux rope
• Can Injection Model Replenish the Filaments in Weak Magnetic Environment?
• Revisiting the Spectral Features of Ellerman Bombs and UV Bursts. I. Radiative Hydrodynamic Simulations