The magnetic flux rope (MFR) is believed to be the underlying magnetic structure of coronal mass ejections (CMEs). However, it remains unclear how an MFR evolves into and forms the multi-component structure of a CME. In this paper, we perform a comprehensive study of an extreme-ultraviolet (EUV) MFR eruption on 2013 May 22 by tracking its morphological evolution, studying its kinematics, and quantifying its thermal property. As EUV brightenings begin, the MFR starts to rise slowly and shows helical threads winding around an axis. Meanwhile, cool filamentary materials descend spirally down to the chromosphere. These features provide direct observational evidence of intrinsically helical structure of the MFR. Through detailed kinematical analysis, we find that the MFR evolution has two distinct phases: a slow rise phase and an impulsive acceleration phase. We attribute the first phase to the magnetic reconnection within the quasi-separatrix layers surrounding the MFR, and the much more energetic second phase to the fast magnetic reconnection underneath the MFR. We suggest that the transition between these two phases is caused by the torus instability. Moreover, we identify that the MFR evolves smoothly into the outer corona and appears as a coherent structure within the white-light CME volume. The MFR in the outer corona was enveloped by bright fronts that originated from plasma pile-up in front of the expanding MFR. The fronts are also associated with the preceding sheath region followed by the outmost MFR-driven shock.

High-energy particles were recorded by the near-Earth spacecraft and groundbased neutron monitors (NMs) on 2012 May 17. This event was the first Ground Level Enhancement (GLE) of the solar cycle 24. In present study, we try to identify the acceleration source(s) of solar energetic particles (SEPs) by combining in-situ particle measurements from W IND/3DP, GOES 13, and solar cosmic rays (SCRs) registered by several NMs, as well as the remote-sensing solar observations from SDO/AIA, SOHO/LASCO, and RHESSI. We derive the interplanetary magnetic field (IMF) path length (1.25 ± 0.05 AU) and solar particle release (SPR) time (01:29 ± 00:01 UT) of the first arriving electrons by using their velocity dispersion and taking into account the contamination effects. It is found that the electron impulsive injection phase, indicated by the dramatic change of spectral index, is consistent with the flare non-thermal emission and type III radio bursts. Based on the potential field source surface (PFSS) concept, a modeling of the open-field lines rooted in the active region (AR) has been performed to provide escaping channels for flare-accelerated electrons. Meanwhile, relativistic protons are found to be released ∼10 min later than the electrons, assuming their scatter-free travel along the same IMF path length. Combining multi-wavelength imaging data on the prominence eruption and coronal mass ejection (CME), we obtain some evidence of that GLE protons, with estimated kinetic energy of ∼1.12 GeV, are probably accelerated by the CME-driven shock when it travels to ∼3.07 solar radii. The time-of-maximum (TOM) spectrum of protons is typical for the shock wave acceleration.

An X17.2 solar flare occurred on 2003 October 28, accompanied by multi-wavelength emissions and a high flux of relativistic particles observed at 1 AU. We present the analytic results of the TRACE, SOHO, RHESSI, ACE, GOES, hard X-ray (INTEGRAL satellite), radio (Ondeřejov radio telescope), and neutron monitor data. It is found that the inferred magnetic reconnection electric field correlates well with the hard X-ray, gamma-ray, and neutron emission at the Sun. Thus the flare's magnetic reconnection probably makes a crucial contribution to the prompt relativistic particles, which could be detected at 1 AU. Since the neutrons were emitted a few minutes before the injection of protons and electrons, we propose a magnetic-field evolution configuration to explain this delay. We do not exclude the effect of CME-driven shock, which probably plays an important role in the delayed gradual phase of solar energetic particles.

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