On The Relationship Between Magnetic Cancellation and UV Burst Formation

TL;DR

This study investigates the link between magnetic cancellation events and UV burst formation on the Sun, analyzing observational data to estimate energy release and dynamics, and finding cancellation rates sufficient but not necessary for UV bursts.

Contribution

The paper provides the first detailed analysis connecting magnetic cancellation rates with UV burst energetics using multi-instrument solar observations.

Findings

Cancellation features have lifetimes of hours and rates of 10^14-10^15 Mx s^-1.

Estimated energy release from cancellation can power UV bursts like Ellerman bombs.

Cancellation is sufficient but not necessary for UV burst formation.

Abstract

Burst-like events with signatures in the UV are often observed co-spatial to strong line-of-sight photospheric magnetic fields. Several authors, for example, have noted the spatial relationship between Ellerman bombs (EBs) and Moving Magnetic Features (MMFs), regions of flux which disconnect from a sunspot or pore before propagating away in the moat flow and often displaying evidence of cancellation. In this article, data collected by the Solar Dynamics Observatory's Helioseismic and Magnetic Imager and Atmospheric Imaging Assembly are analysed in an attempt to understand the potential links between such cancellation and UV burst formation. Two MMFs from AR 11579, three bi-poles from AR 11765, and six bi-poles (four of which were co-spatial to IRIS bursts) in AR 11850 were identified for analysis. All of these cancellation features were found to have lifetimes of the order hours and cancellation rates of the order 10^14-10^15 Mx s^-1. H-alpha line wing data from the Dunn Solar Telescope's Interferometric BIdimensional Spectrometer were also available for AR 11579 facilitating a discussion of links between MMFs and EBs. Using an algebraic model of photospheric magnetic reconnection, the measured cancellation rates are then used to ascertain estimates of certain quantities (such as up-flow speeds, jet extents, and potential energy releases) which compared reasonably to the properties of EBs reported within the literature. Our results suggest that cancellation rates of the order measured here are capable of supplying enough energy to drive certain UV bursts (including EBs), however, they are not a guaranteeing condition for burst formation.