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Ultra-long and quite thin coronal loop without significant expansion
Alternative TitleWOS:000553454900001
Li, Dong1; Yuan, Ding2; Goossens, Marcel3; Van Doorsselaere, Tom3; Su, Wei4; Wang, Ya; Su, Yang5; Ning, Zongjun5
Source PublicationASTRONOMY & ASTROPHYSICS
2020
Volume639Pages:A114
DOI10.1051/0004-6361/202038433
ISSN0004-6361
Language英语
KeywordSun: corona Sun: UV radiation Sun: magnetic fields Sun: activity EUV IMAGING SPECTROMETER ACTIVE-REGION LOOPS SOHO/CDS
AbstractContext. Coronal loops are the basic building blocks of the solar corona. They are related to the mass supply and heating of solar plasmas in the corona. However, their fundamental magnetic structures are still not well understood. Most coronal loops do not expand significantly, but the diverging magnetic field would have an expansion factor of about 5-10 over one pressure scale height. Aims. We investigate a unique coronal loop with a roughly constant cross section. The loop is ultra long and quite thin. A coronal loop model with magnetic helicity is presented to explain the small expansion of the loop width. Methods. This coronal loop was predominantly detectable in the 171 angstrom channel of the Atmospheric Imaging Assembly (AIA). Then, the local magnetic field line was extrapolated within a model of the potential field source-surface. Finally, the differential emission measure analysis made from six AIA bandpasses was applied to obtain the thermal properties of this loop. Results. This coronal loop has a projected length of roughly 130 Mm, a width of about 1.5 +/- 0.5 Mm, and a lifetime of about 90 min. It follows an open magnetic field line. The cross section expanded very little (i.e., 1.5-2.0) along the loop length during its whole lifetime. This loop has a nearly constant temperature at about 0.7 +/- 0.2 MK, but its density exhibits the typical structure of a stratified atmosphere. Conclusions. We use the theory of a thin twisted flux tube to construct a model for this nonexpanding loop and find that with sufficient twist, a coronal loop can indeed attain equilibrium. However, we cannot rule out other possibilities such as footpoint heating by small-scale reconnection or an elevated scale height by a steady flow along the loop.
Indexed BySCI
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Document Type期刊论文
Identifierhttp://ir.nssc.ac.cn/handle/122/7645
Collection中国科学院国家空间科学中心
Affiliation1.Chinese Acad Sci, Key Lab Dark Matter & Space Astron, Purple Mt Observ, Nanjing 210033, Peoples R China
2.Chinese Acad Sci, State Key Lab Space Weather, Beijing 100190, Peoples R China
3.Harbin Inst Technol, Inst Space Sci & Appl Technol, Shenzhen 518055, Peoples R China
4.Katholieke Univ Leuven, Dept Math, Ctr Math Plasma Astrophys, Celestijnenlaan 200B, B-3001 Leuven, Belgium
5.Huazhong Univ Sci & Technol, MOE Key Lab Fundamental Phys Quant Measurements, Sch Phys, Wuhan 430074, Peoples R China
6.Univ Sci & Technol China, Sch Astron & Space Sci, Hefei 230026, Peoples R China
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GB/T 7714
Li, Dong,Yuan, Ding,Goossens, Marcel,et al. Ultra-long and quite thin coronal loop without significant expansion[J]. ASTRONOMY & ASTROPHYSICS,2020,639:A114.
APA Li, Dong.,Yuan, Ding.,Goossens, Marcel.,Van Doorsselaere, Tom.,Su, Wei.,...&Ning, Zongjun.(2020).Ultra-long and quite thin coronal loop without significant expansion.ASTRONOMY & ASTROPHYSICS,639,A114.
MLA Li, Dong,et al."Ultra-long and quite thin coronal loop without significant expansion".ASTRONOMY & ASTROPHYSICS 639(2020):A114.
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