A multi-instrument study of ultraviolet bursts and associated surges in AR 12957

TL;DR

This study investigates the complex relationship between ultraviolet bursts and solar surges in active region AR 12957 using multi-instrument observations, revealing magnetic reconnection as a key driver and highlighting the role of magnetic topology and flux movement.

Contribution

It provides the first detailed multi-instrument analysis linking UV bursts and surges, emphasizing magnetic reconnection and flux dynamics in active region AR 12957.

Findings

UV bursts are associated with magnetic flux interactions and reconnection.

Surges vary in temperature, size, and duration, linked to magnetic activity.

Magnetic flux movement influences surge formation and dynamics.

Abstract

The relationship between UV Bursts and solar surges is complex, with these events sometimes being observed together and sometimes being observed independently. Why this sporadic association exists is unknown, however, it likely relates to the physical conditions at the site of the energy release that drives these events. Here, we aim to better understand the relationship between UV Bursts and solar surges through a multi-instrument analysis of several associated events that occurred around the trailing sunspot in AR 12957. We use data from Solar Orbiter, the Solar Dynamics Observatory (SDO), and the Interface Region Imaging Spectrograph (IRIS) to achieve our aims. These data were sampled on 3rd March 2022 between 09:30:30 UT and 11:00:00 UT, during which time a coordinated observing campaign associated with the Slow Solar Wind Connection Solar Orbiter Observing Plan took place. Numerous small-scale negative polarity magnetic magnetic features (MMFs) are observed to move quickly (potentially up to 3.3 km/s) away from a sunspot until they collide with a more stable positive polarity plage region around 7 Mm away. Several UV Bursts are identified in IRIS slit-jaw imager (SJI) 1400 {\AA} data co-spatial to where these opposite polarity fields interact, with spatial scales (2 Mm<) and lifetimes (20< min) larger than typical values for such events. Two surges are also observed to occur at these locations, with one being short (5 Mm) and hot (bright in IRIS SJI images), whilst the other is a cooler (dark in coronal imaging channels), longer surge that appears to fill an active region loop. Magnetic reconnection between the negative polarity MMFs around the sunspot and the positive polarity plage region appears to be the driver of these events. Both the speed of the MMFs and the locally open magnetic topology of the plage region could possibly be important for forming the surges.