2010/11/22 by Rui Liu, Chang Liu, Shuo Wang +2 · 5 citations
Physics and Astronomy · #Astro and Planetary Science #Astrophysics #Coronal loop #Coronal mass ejection #Flare #Flux (metallurgy) #Loop (graph theory) #Magnetic field #Magnetic flux #Magnetic reconnection #Magnetogram #Physics #Solar and Space Plasma Dynamics #Solar flare #Solar wind #Stellar, planetary, and galactic studies #astro-ph.SR
paper · pdf · doi:10.1088/2041-8205/725/1/l84
published as 2010, ApJL, 725, L84-L90
openalex publication_date 2010/11/22 · arxiv created 2010/12/02 · arxiv updated 2010/12/03 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Sigmoids are one of the most important precursor structures for solar eruptions. In this Letter, we study a sigmoid eruption on 2010 August 1 with EUV data obtained by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamic Observatory ( SDO ). In AIA 94 Å (Fe xviii ; 6 MK), topological reconfiguration due to tether-cutting reconnection is unambiguously observed for the first time, i.e., two opposite J-shaped loops reconnect to form a continuous S-shaped loop, whose central portion is dipped and aligned along the magnetic polarity inversion line (PIL), and a compact loop crossing the PIL. A causal relationship between photospheric flows and coronal tether-cutting reconnections is evidenced by the detection of persistent converging flows toward the PIL using line-of-sight magnetograms obtained by the Helioseismic and Magnetic Imager on board SDO . The S-shaped loop remains in quasi-equilibrium in the lower corona for about 50 minutes, with the central dipped portion rising slowly at ∼10 km s −1 . The speed then increases to ∼60 km s −1 about 10 minutes prior to the onset of a GOES -class C3.2 flare, as the S-shaped loop speeds up its transformation into an arch-shaped loop, which eventually leads to a loop-like coronal mass ejection. The AIA observations combined with Hα filtergrams as well as hard X-ray imaging and spectroscopy are consistent with most flare loops being formed by reconnection of the stretched legs of less-sheared J-shaped loops that envelopes the rising flux rope, in agreement with the standard tether-cutting scenario.