Sigmoid-to-flux-rope transition leading to a loop-like coronal mass ejection

Document Type

Article

Publication Date

12-10-2010

Abstract

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 tethercutting 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 looplike 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 lesssheared J-shaped loops that envelopes the rising flux rope, in agreement with the standard tether-cutting scenario. © 2010. The American Astronomical Society. All rights reserved.

Identifier

78650251152 (Scopus)

Publication Title

Astrophysical Journal Letters

External Full Text Location

https://doi.org/10.1088/2041-8205/725/1/L84

e-ISSN

20418213

ISSN

20418205

First Page

L84

Last Page

L90

Issue

1 PART 2

Volume

725

Grant

0849453

Fund Ref

National Science Foundation

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