The term "ultraviolet (UV) burst" is introduced to describe small, intense, transient brightenings in ultraviolet images of solar active regions. We inventorize their properties and provide a definition based on image sequences in transition-region lines. Coronal signatures are rare, and most bursts are associated with small-scale, canceling opposite-polarity fields in the photosphere that occur in emerging flux regions, moving magnetic features in sunspot moats, and sunspot light bridges. We also compare UV bursts with similar transition-region phenomena found previously in solar ultraviolet spectrometry and with similar phenomena at optical wavelengths, in particular Ellerman bombs. Akin to the latter, UV bursts are probably small-scale magnetic reconnection events occurring in the low atmosphere, at photospheric and/or chromospheric heights. Their intense emission in lines with optically thin formation gives unique diagnostic opportunities for studying the physics of magnetic reconnection in the low solar atmosphere. This paper is a review report from an International Space Science Institute team that met in 2016-2017.
@article{arxiv.1805.05850,
title = {Solar ultraviolet bursts},
author = {Peter R. Young and Hui Tian and Hardi Peter and Robert J. Rutten and Chris J. Nelson and Zhenghua Huang and Brigitte Schmieder and Gregal J. M. Vissers and Shin Toriumi and Luc H. M. Rouppe van der Voort and Maria S. Madjarska and Sanja Danilovic and Arkadiusz Berlicki and L. P. Chitta and Mark C. M. Cheung and Chad Madsen and Kevin P. Reardon and Yukio Katsukawa and Petr Heinzel},
journal= {arXiv preprint arXiv:1805.05850},
year = {2018}
}
Comments
Review article accepted for publication in Space Science Reviews