Small-Scale Eruptions on the Sun

A special issue of Universe (ISSN 2218-1997). This special issue belongs to the section "Space Science".

Deadline for manuscript submissions: 30 June 2024 | Viewed by 2495

Special Issue Editors

National Astronomical Observatories, Chinese Academy of Science, Beijing 100101, China
Interests: solar eruptions; small-scale eruptions; jet; solar magnetic field; coronal loops

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Guest Editor
Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216, China
Interests: solar physics; solar jets; filament eruptions; MHD waves

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Guest Editor
Department of Physics, Aberystwyth University, Ceredigion, Cymru SY23 3BZ, UK
Interests: solar physics; small scale solar feature analysis; flare prediction; machine learning

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Guest Editor
Solar Physics & Space Plasma Research Center (SP2RC), School of Mathematics and Statistics, University of Sheffield, Hounsfield Road S3 7RH, UK
Interests: solar physics; MHD waves; jets; space weather

Special Issue Information

Dear Colleagues,

Small-scale eruptions, that are ubiquitous on the Sun, are found often to be accompanied or associated with different solar magnetic field phenomena. It is the current and widely accepted view that the triggering mechanism is closely related with magnetic reconnection. The study of small-scale eruptions can improve the understanding of solar atmospheric heating from chromosphere to corona.

Based on their observed characteristics, including e.g. various sizes, dominant temperatures, and the actual wavelengths that are used to observe, small-scale eruptions have different names including spicules, jets, bright-points, camp-fire, nano-flares etc. Since the first modern observations of these small-scale dynamic phenomena in the solar atmosphere, the understanding of these highly localized eruptions has been advanced greatly, thanks also to the development of MHD and plasma-astrophysics theories, the improvement in computational powers, and to the realization of a number of state-of-the-arts observational facilities with high spatial and spectral resolution and cadence. 

This Special Issue is devoted to a variety of research in small-scale eruptions. We encourage submissions ranging from observations and theory to numerical, statistical, and machine learning modeling, in order to foster collaborations across the relevant communities.

Dr. Jie Chen
Dr. Yuandeng Shen
Dr. Marianna Korsos
Prof. Dr. Robertus Erdelyi
Guest Editors

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Keywords

  • solar eruption
  • magnetic reconnection
  • coronal heating
  • magneto-hydrodynamics (MHD)
  • spicules
  • jets
  • bright points
  • nano-flares
  • camp fires

Published Papers (2 papers)

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Research

15 pages, 1536 KiB  
Article
A Partial Eruption of a Sigmoid Filament in the Small Dipole Active Region 12734
by Jihong Liu, Yin Zhang, Yuhong Zheng, Yu Liu and Jie Chen
Universe 2024, 10(1), 42; https://doi.org/10.3390/universe10010042 - 16 Jan 2024
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Abstract
We present a detailed analysis of a partial eruption of a sigmoid filament lying along the polarity inversion line (PIL) of the small active region (AR) NOAA 12734 (with an area of 1.44 ×103 square megameters). The active filament was rooted [...] Read more.
We present a detailed analysis of a partial eruption of a sigmoid filament lying along the polarity inversion line (PIL) of the small active region (AR) NOAA 12734 (with an area of 1.44 ×103 square megameters). The active filament was rooted in a dipole sunspot of the AR. The eruption was associated with a C1.3 flare and subsequent large-scale coronal disturbances. During its solar disk passage before the flare, the AR had the following characteristics: (1) Most of the time, the magnetic field lines in the AR showed a sigmoidal structure (‘L1’) in the low corona and arc-shaped loops (i.e., ‘L2’) in the upper atmosphere. (2) An ‘X’-shaped structure was formed between the original ‘S’-shaped magnetic loop (‘L1’) and the newly rising one (‘L3’) between the main positive and negative magnetic polarities of the sunspots, and the intersection point of flux ropes ‘L1’ and ‘L3’ corresponds well with the area where the initial extreme-ultraviolet (EUV) 1600 Å brightening of the flare occurred. (3) The AR disobeyed the hemispherical helicity rule and had magnetic twist and writhe of the same signs, i.e., its magnetic helicity/current helicity were positive in the northern hemisphere. (4) Sustained magnetic emergence and cancellation occurred before the flare. Therefore, the magnetic reconnection of highly twisted helical flux ropes under the confinement of the overlying magnetic fields is probably responsible for the partial eruption of the filament. Full article
(This article belongs to the Special Issue Small-Scale Eruptions on the Sun)
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9 pages, 970 KiB  
Article
N-S Asymmetry and Solar Cycle Distribution of Superactive Regions from 1976 to 2017
by Ming-Xian Zhao, Gui-Ming Le and Yong-Hua Liu
Universe 2022, 8(11), 605; https://doi.org/10.3390/universe8110605 - 17 Nov 2022
Cited by 2 | Viewed by 1036
Abstract
There were 51 superactive regions (SARs) during solar cycles (SCs) 21–24. We divided the SARs into SARs1, which produced extreme space weather events including ≥X5.0 flares, ground level events (GLEs), and super geomagnetic storms (SGSs, Dst < −250 nT), and SARs [...] Read more.
There were 51 superactive regions (SARs) during solar cycles (SCs) 21–24. We divided the SARs into SARs1, which produced extreme space weather events including ≥X5.0 flares, ground level events (GLEs), and super geomagnetic storms (SGSs, Dst < −250 nT), and SARs2, which did not produce extreme space weather events. The total number of SARs1 and SARs2 are 31 and 20, respectively. The statistical results showed that 35.5%, 64.5%, and 77.4% of the SARs1 appeared in the ascending phase, descending phase, and in the period from two years before to the three years after the solar maximum, respectively, whereas 50%, 50%, and 100% of the SARs2 appeared in the ascending phase, descending phase, and in the period from two years before to the three years after the solar maximum, respectively. The total number of SARs during an SC has a good association with the SC amplitude, implying that an SC with a higher amplitude will have more SARs than that with a lower amplitude. However, the largest flare index of a SAR within an SC has a poor association with the SC amplitude, suggesting that a weak cycle may have a SAR that may produce a series of very strong solar flares. The analysis of the north–south asymmetry of the SARs showed that SARs1 dominated in the southern hemisphere of the sun during SCs 21–24. The SAR2 dominated in the different hemispheres by turns for different SCs. The solar flare activities caused by the SARs with source locations in the southern hemisphere of the sun were much stronger than those caused by the SARs with source locations in the northern hemisphere of the sun during SCs 21–24. Full article
(This article belongs to the Special Issue Small-Scale Eruptions on the Sun)
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