Reconnection brightenings in the quiet solar photosphere

TL;DR

This paper reports the discovery and characterization of a new quiet-Sun phenomenon called QSEBs, which are small, short-lived brightenings in the H-alpha wing indicating photospheric magnetic reconnection in quiet regions.

Contribution

The paper introduces QSEBs as a new type of quiet-Sun brightening, distinct from Ellerman bombs, with detailed observational measurements and evidence of their association with photospheric reconnection.

Findings

QSEBs are smaller and less intense than Ellerman bombs.

QSEBs have lengths less than 0.5 arcsec, widths of 0.21 arcsec, and last less than a minute.

QSEBs are linked to photospheric reconnection in quiet solar regions.

Abstract

We describe a new quiet-Sun phenomenon which we call "Quiet-Sun Ellerman-like Brightenings" (QSEB). QSEBs are similar to Ellerman bombs (EB) in some respects but differ significantly in others. EBs are transient brightenings of the wings of the Balmer H-alpha line that mark strong-field photospheric reconnection in complex active regions. QSEBs are similar but smaller and less intense Balmer-wing brightenings that occur in quiet areas away from active regions. In the H-alpha wing we measure typical lengths of less than 0.5 arcsec, widths of 0.21 arcsec, and lifetimes of less than a minute. We discovered them using high-quality H-alpha imaging spectrometry from the Swedish 1-m Solar Telescope (SST) and show that in lesser-quality data they cannot be distinguished from more ubiquitous facular brightenings, nor in the ultraviolet diagnostics currently available from space platforms. We add evidence from concurrent SST spectropolarimetry that QSEBs also mark photospheric reconnection events, but in quiet regions on the solar surface.