X. Cheng

TWIST ACCUMULATION AND TOPOLOGY STRUCTURE OF A SOLAR MAGNETIC FLUX ROPE

To study the buildup of a magnetic flux rope before a major flare and coronal mass ejection (CME), we compute the magnetic helicity injection, twist accumulation, and topology structure of the three-dimensional (3D) magnetic field, which is derived by the nonlinear force-free field model. The Extreme-ultraviolet Imaging Telescope on board the Solar and Heliospheric Observatory observed a series of confined flares without any CME before a major flare with a CME at 23:02 UT on 2005 January 15 in active region NOAA 10720. We derive the vector velocity at eight time points from 18:27 UT to 22:20 UT with the differential affine velocity estimator for vector magnetic fields, which were observed by the Digital Vector Magnetograph at Big Bear Solar Observatory. The injected magnetic helicity is computed with the vector magnetic and velocity fields. The helicity injection rate was (– 16.47 ± 3.52) × 1040 Mx2 hr–1. We find that only about 1.8% of the injected magnetic helicity became the internal helicity of the magnetic flux rope, whose twist increasing rate was –0.18 ± 0.08 Turns hr–1. The quasi-separatrix layers (QSLs) of the 3D magnetic field are computed by evaluating the squashing degree, Q. We find that the flux rope was wrapped by QSLs with large Q values, where the magnetic reconnection induced by the continuously injected magnetic helicity further produced the confined flares. We suggest that the flux rope was built up and heated by the magnetic reconnection in the QSLs.

IMAGING AND SPECTROSCOPIC DIAGNOSTICS ON THE FORMATION OF TWO MAGNETIC FLUX ROPES REVEALED BY SDO/AIA AND IRIS

Helical magnetic flux rope (MFR) is a fundamental structure of corona mass ejections (CMEs) and has been discovered recently to exist as a sigmoidal channel structure prior to its eruption in the extreme ultraviolet (EUV) high temperature passbands of the Atmospheric Imaging Assembly (AIA). However, when and where the MFR is built up are still elusive. In this paper, we investigate two MFRs (MFR1 and MFR2) in detail, whose eruptions produced two energetic solar flares and CMEs on 2014 April 18 and 2014 September 10, respectively. The AIA EUV images reveal that for a long time prior to their eruption, both MFR1 and MFR2 are under formation, which is probably through magnetic reconnection between two groups of sheared arcades driven by the shearing and converging flows in the photosphere near the polarity inversion line. At the footpoints of the MFR1, the \textit{Interface Region Imaging Spectrograph} Si IV, C II, and Mg II lines exhibit weak to moderate redshifts and a non-thermal broadening in the pre-flare phase. However, a relatively large blueshift and an extremely strong non-thermal broadening are found at the formation site of the MFR2. These spectral features consolidate the proposition that the reconnection plays an important role in the formation of MFRs. For the MFR1, the reconnection outflow may propagate along its legs, penetrating into the transition region and the chromosphere at the footpoints. For the MFR2, the reconnection probably takes place in the lower atmosphere and results in the strong blueshift and non-thermal broadening for the Mg II, C II, and Si IV lines.

MULTIWAVELENGTH OBSERVATIONS OF A PARTIALLY ERUPTIVE FILAMENT ON 2011 SEPTEMBER 8

In this paper, we report our multiwavelength observations of a partial filament eruption event in NOAA active region 11283 on 2011 September 8. A magnetic null point and the corresponding spine and separatrix surface are found in the active region. Beneath the null point, a sheared arcade supports the filament along the highly complex and fragmented polarity inversion line. After being activated, the sigmoidal filament erupted and split into two parts. The major part rose at the speeds of 90

Extreme ultraviolet imaging of three-dimensional magnetic reconnection in a solar eruption

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A TYPE II RADIO BURST WITHOUT A CORONAL MASS EJECTION

150 km s

Reversal of the Apoptotic Resistance of Non-Small-Cell Lung Carcinoma towards TRAIL by Natural Product Toosendanin

^{-1}

Sunspot Rotation as a Driver of Major Solar Eruptions in the NOAA Active Region 12158

before reaching the maximum apparent height of

DYNAMIC EVOLUTION OF AN X-SHAPED STRUCTURE ABOVE A TRANS-EQUATORIAL QUADRUPOLE SOLAR ACTIVE REGION GROUP

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INVESTIGATING THE CONDITIONS OF THE FORMATION OF A TYPE II RADIO BURST ON 2014 JANUARY 8

115 Mm. Afterwards, it returned to the solar surface in a bumpy way at the speeds of 20

Toosendanin inhibits adipogenesis by activating Wnt/β-catenin signaling

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