UV bursts: magnetic reconnection in the lower solar atmosphere

IRIS observations have revealed numerous intense, compact and transient brightenings at typical transition region temperatures (around 100,000 K). UV bursts are found to be markers of solar flux emergence/AR formation, and many of them appear to be associated with small-scale flux cancellation. UV bursts could be located at magnetic null points, bald patches, or other regions of large squashing factor. Some Ellerman bombs (EBs) are found to be connected to UV bursts, and these UV bursts have a tendency to appear at the upper parts of their associated flame-like EBs in near-limb observations. The intensity variations of most EB-related UV bursts and their corresponding EBs match well. These results suggest that some UV bursts and EBs likely form at different heights during a common reconnection process. In addition, we find that UV bursts reveal no obvious coronal signatures from the observations of SDO/AIA and Hinode/EIS.