Spectroscopic Case Studies of Four Long-duration Transition-region Explosive Events

Fuente: arXiv
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Autori principali: Zhou, Yi'an, Yan, Xiaoli, Xue, Zhike, Yang, Liheng, Wang, Jincheng, Xu, Zhe
Natura: Preprint
Pubblicazione: 2026
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author Zhou, Yi'an
Yan, Xiaoli
Xue, Zhike
Yang, Liheng
Wang, Jincheng
Xu, Zhe
author_facet Zhou, Yi'an
Yan, Xiaoli
Xue, Zhike
Yang, Liheng
Wang, Jincheng
Xu, Zhe
contents This work presents a detailed spectroscopic case study of four long-duration transition-region (TR) explosive events (EEs) observed in NOAA Active Region 13213 on 2023 February 10 using the Interface Region Imaging Spectrograph. The dynamic spectral evolution of each event is tracked through multicomponent Gaussian fitting of the Si IV 1403 Å line profiles. Three recurrent spectral morphologies are identified and characterized: bilateral wing enhancement, exclusive red-wing enhancement, and exclusive blue-wing enhancement, among which bilateral enhancement is the most common in the studied cases. Throughout their lifetimes of 20-25 minutes, these events display sustained and evolving bidirectional flows, with high-velocity components ($|v|$ > 100 km $s^{-1}$) emerging in late phases. These spectral signatures are interpreted as evidence of ongoing or recurrent magnetic reconnection, where bilateral profiles correspond to bidirectional outflows, and exclusive wing enhancements represent geometric or evolutionary phases of the same process. In contrast, cotemporal flare ribbons and loop structures exhibit pronounced, unidirectional redshifts. This study underscores that significant non-Gaussian wing enhancement, rather than exclusively high speed, constitutes a defining spectroscopic signature of EEs, and provides detailed kinematic constraints on the dynamics of such TR EEs.
format Preprint
id arxiv_https___arxiv_org_abs_2604_01774
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Spectroscopic Case Studies of Four Long-duration Transition-region Explosive Events
Zhou, Yi'an
Yan, Xiaoli
Xue, Zhike
Yang, Liheng
Wang, Jincheng
Xu, Zhe
Solar and Stellar Astrophysics
This work presents a detailed spectroscopic case study of four long-duration transition-region (TR) explosive events (EEs) observed in NOAA Active Region 13213 on 2023 February 10 using the Interface Region Imaging Spectrograph. The dynamic spectral evolution of each event is tracked through multicomponent Gaussian fitting of the Si IV 1403 Å line profiles. Three recurrent spectral morphologies are identified and characterized: bilateral wing enhancement, exclusive red-wing enhancement, and exclusive blue-wing enhancement, among which bilateral enhancement is the most common in the studied cases. Throughout their lifetimes of 20-25 minutes, these events display sustained and evolving bidirectional flows, with high-velocity components ($|v|$ > 100 km $s^{-1}$) emerging in late phases. These spectral signatures are interpreted as evidence of ongoing or recurrent magnetic reconnection, where bilateral profiles correspond to bidirectional outflows, and exclusive wing enhancements represent geometric or evolutionary phases of the same process. In contrast, cotemporal flare ribbons and loop structures exhibit pronounced, unidirectional redshifts. This study underscores that significant non-Gaussian wing enhancement, rather than exclusively high speed, constitutes a defining spectroscopic signature of EEs, and provides detailed kinematic constraints on the dynamics of such TR EEs.
title Spectroscopic Case Studies of Four Long-duration Transition-region Explosive Events
topic Solar and Stellar Astrophysics
url https://arxiv.org/abs/2604.01774