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Title: Extreme Red-wing Enhancements of UV Lines during the 2022 March 30 X1.3 Solar Flare
Abstract Here, we present the study of a compact emission source during an X1.3 flare on 2022 March 30. Within a ∼41 s period (17:34:48 UT to 17:35:29 UT), Interface Region Imaging Spectrograph observations show spectral lines of Mgii, Cii, and Siivwith extremely broadened, asymmetric red wings. This source of interest (SOI) is compact, ∼1.″6, and is located in the wake of a passing ribbon. Two methods were applied to measure the Doppler velocities associated with these red wings: spectral moments and multi-Gaussian fits. The spectral-moments method considers the averaged shift of the lines, which are 85, 125, and 115 km s−1for the Mgii, Cii, and Siivlines respectively. The red-most Gaussian fit suggests a Doppler velocity up to ∼160 km s−1in all of the three lines. Downward mass motions with such high speeds are very atypical, with most chromospheric downflows in flares on the order 10–100 km s−1. Furthermore, extreme-UV (EUV) emission is strong within flaring loops connecting two flare ribbons located mainly to the east of the central flare region. The EUV loops that connect the SOI and its counterpart source in the opposite field are much less brightened, indicating that the density and/or temperature is comparatively low. These observations suggest a very fast downflowing plasma in the transition region and upper chromosphere, which decelerates rapidly since there is no equivalently strong shift of the O I chromospheric lines. This unusual observation presents a challenge that models of the solar atmosphere’s response to flares must be able to explain.  more » « less
Award ID(s):
2309939 1821294 2108235 2228996
PAR ID:
10496769
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
IOP Publishing
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
958
Issue:
1
ISSN:
0004-637X
Page Range / eLocation ID:
67
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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