An in-depth analysis of quiet-Sun IRIS Brightenings

TL;DR

This study uses advanced detection algorithms on high-resolution IRIS data to analyze small-scale brightenings in the quiet Sun, revealing their characteristics, dynamics, and magnetic nature, and comparing different solar regions.

Contribution

It introduces a novel filter-detection algorithm for near-noise-level brightenings and provides a detailed analysis of their properties and magnetic origins in quiet-Sun regions.

Findings

Active brightenings travel shorter distances and slower than quiet-Sun counterparts.

Brightenings show blue-shifts and may rise from chromosphere into transition region.

Bright points are likely magnetic reconnection events occurring along current sheets.

Abstract

Small-scale brightenigs are ubiquitous, dynamic and energetic phenomena found in the chromopshere. An advanced filter-detection algorithm applied to high-resolution observations from the Interface Region Imaging Spectrograph enables the detection of these brightenings close to the noise level. This algorithm also tracks the movement of these brightenings and extracts their characteristics. This work outlines the results of an in-depth analysis of a quiet-Sun dataset including a comparison of a brighter domain - associated with a super-granular boundary - to the quiescent inter-network domains. Several characteristics of brightenings from both domains are extracted and analysed, providing a range of sizes, durations, brightness values, travel distances, and speeds. The ``Active" quiet-Sun events tend to travel shorter distances and at slower speeds along the plane-of-sky than their ``True" quiet-Sun counterparts. These results are consistent with the magnetic field model of super-granular photospheric structures and the magnetic canopy model of the chromosphere above. Spectroscopic analyses reveal that BPs demonstrate blue-shift (as well as some bi-directionality) and that they may rise from the chromosphere into the TR. We believe these bright points to be magnetic in nature, are likely the result of magnetic reconnection, and follow current sheets between magnetic field gradients, rather than along magnetic field lines themselves.