Speaker
Description
First Name: Ziwen
Last Name: Huang
Affiliation: Max Planck Institute for Solar System Research
All Authors: Ziwen Huang; L. P. Chitta; L. Teriaca
Abstract: Flare ribbons, the footpoints of newly reconnected magnetic loops, are commonly associated with strong plasma flows and pronounced non-thermal line broadening in transition region resulting from impulsive energy deposition. However, the mechanism governing energy transport into flare ribbons is not fully understood. Here, we report on a unique case of a remote flare ribbon observed during the M7.7-class event on 30 September 2024, using coordinated observations from Solar Dynamics Observatory, Interface Region Imaging Spectrograph (IRIS) and Solar Orbiter. Analysis of imaging data from the Extreme-Ultraviolet Imager and the Atmospheric Imaging Assembly reveals small-scale downflow signatures at the ribbon location, while spectroscopic analysis of Si IV profiles from IRIS shows an intriguing behaviour: The brightest ribbon pixels exhibit Si IV profiles that are unexpectedly narrow, with non-thermal widths on the order of 10 km/s, and are well approximated by a single Gaussian. Such narrow profiles with strong emissions and the negligible line-of-sight velocity clearly differ from the broadened and shifted spectra typically reported for flare ribbons, suggesting that flare ribbons do exhibit a wider diversity of transition region responses. We present these multi-instrument observations and discuss possible interpretations of these narrow line profiles in ribbons.