Ellerman bombs at high resolution III. Simultaneous observations with IRIS and SST

TL;DR

This study combines high-resolution ultraviolet and H-alpha observations to analyze Ellerman bombs, revealing their magnetic reconnection processes and heating effects within the solar photosphere and chromosphere.

Contribution

It provides detailed spectroscopic evidence of Ellerman bombs' reconnection and heating, integrating IRIS, SST, and SDO data for comprehensive analysis.

Findings

Ellerman bombs indicate reconnection between bipolar kilogauss flux tubes.

Reconnection heats photospheric gas to transition region and coronal temperatures.

Similar phenomena, like small flaring arch filaments, involve higher-altitude reconnection and produce hot arches.

Abstract

Ellerman bombs are transient brightenings of the extended wings of the solar Balmer lines in emerging active regions. We describe their properties in the ultraviolet lines sampled by the Interface Region Imaging Spectrograph (IRIS), using simultaneous imaging spectroscopy in H$\alpha$ with the Swedish 1-m Solar Telescope (SST) and ultraviolet images from the Solar Dynamics Observatory for Ellerman bomb detection and identification. We select multiple co-observed Ellerman bombs for detailed analysis. The IRIS spectra strengthen the view that Ellerman bombs mark reconnection between bipolar kilogauss fluxtubes with the reconnection and the resulting bi-directional jet located within the solar photosphere and shielded by overlying chromospheric fibrils in the cores of strong lines. The spectra suggest that the reconnecting photospheric gas underneath is heated sufficiently to momentarily reach stages of ionization normally assigned to the transition region and the corona. We also analyze similar outburst phenomena that we classify as small flaring arch filaments and ascribe to higher-located reconnection. They have different morphology and produce hot arches in million-Kelvin diagnostics.