TY  - JOUR
A1  - Chen, Jun
A1  - Liu, Rui
A1  - Liu, Kai
A1  - Awasthi, Arun Kumar
A1  - Zhang, Peijin
A1  - Wang, Yuming
A1  - Kliem, Bernhard
T1  - Extreme-ultraviolet late phase of solar flares
T2  - The astrophysical journal : an international review of spectroscopy and astronomical physics
N2  - A second peak in the extreme ultraviolet sometimes appears during the gradual phase of solar flares, which is known as the EUV late phase (ELP). Stereotypically ELP is associated with two separated sets of flaring loops with distinct sizes, and it has been debated whether ELP is caused by additional heating or extended plasma cooling in the longer loop system. Here we carry out a survey of 55 M-and-above GOES-class flares with ELP during 2010-2014. Based on the flare-ribbon morphology, these flares are categorized as circular-ribbon (19 events), two-ribbon (23 events), and complex-ribbon (13 events) flares. Among them, 22 events (40%) are associated with coronal mass ejections, while the rest are confined. An extreme ELP, with the late-phase peak exceeding the main-phase peak, is found in 48% of two-ribbon flares, 37% of circular-ribbon flares, and 31% of complex-ribbon flares, suggesting that additional heating is more likely present during ELP in two-ribbon than in circular-ribbon flares. Overall, cooling may be the dominant factor causing the delay of the ELP peak relative to the main-phase peak, because the loop system responsible for the ELP emission is generally larger than, and well separated from, that responsible for the main-phase emission. All but one of the circular-ribbon flares can be well explained by a composite "dome-plate" quasi-separatrix layer (QSL). Only half of these show a magnetic null point, with its fan and spine embedded in the dome and plate, respectively. The dome-plate QSL, therefore, is a general and robust structure characterizing circular-ribbon flares.
Y1  - 2020
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/60144
SN  - 0004-637X
SN  - 1538-4357
VL  - 890
IS  - 2
PB  - Institute of Physics Publ.
CY  - London
ER  -