Using Spectra to Characterize the Hot, Dense Ridge in a Two-ribbon Flare
- 1Montana State University
Abstract
Observations of limb flares sometimes show a hot, dense plasma sheet surrounding the expected location of the reconnecting current sheet. Recently, bright linear features, called ridges, seen in overhead views of some disk flares in extreme-ultraviolet images, have been interpreted as the plasma sheet viewed from a different perspective. The overhead view permits the plasma sheet to be associated with a reconnection rate, measured using flare ribbon motion. More information about the plasma sheet might, however, be obtained through spectroscopic measurements of a ridge, but these have not yet been made. In this work we use spectroscopic observations made by the Interface Region Imaging Spectrograph of the 2014 March 29 flare (SOL2014-03-29T17:48) to determine the properties of its ridge. We find a very steady downflow at a speed consistent with the inferred rate of reconnection but little evidence for vigorous plasma turbulence at the base of the plasma sheet. These findings corroborate the basic understanding of flare ridges and motivate a revision to the picture of the hot, dense plasma surrounding the reconnecting current sheet.
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BibTeX
@article{longcope2026using,
title = {{Using Spectra to Characterize the Hot, Dense Ridge in a Two-ribbon Flare}},
author = {Dana Longcope and Roy Smart},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/aea900},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/aea900},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Using Spectra to Characterize the Hot, Dense Ridge in a Two-ribbon Flare
AU - Dana Longcope
AU - Roy Smart
PY - 2026
DA - 2026/10/16
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/aea900
UR - https://iopscience.iop.org/article/10.3847/1538-4357/aea900
AB - Observations of limb flares sometimes show a hot, dense plasma sheet surrounding the expected location of the reconnecting current sheet. Recently, bright linear features, called ridges, seen in overhead views of some disk flares in extreme-ultraviolet images, have been interpreted as the plasma sheet viewed from a different perspective. The overhead view permits the plasma sheet to be associated with a reconnection rate, measured using flare ribbon motion. More information about the plasma sheet might, however, be obtained through spectroscopic measurements of a ridge, but these have not yet been made. In this work we use spectroscopic observations made by the Interface Region Imaging Spectrograph of the 2014 March 29 flare (SOL2014-03-29T17:48) to determine the properties of its ridge. We find a very steady downflow at a speed consistent with the inferred rate of reconnection but little evidence for vigorous plasma turbulence at the base of the plasma sheet. These findings corroborate the basic understanding of flare ridges and motivate a revision to the picture of the hot, dense plasma surrounding the reconnecting current sheet.
SN - 0004-637X
SN - 1538-4357
ER -