The fundamental mechanism initiating coronal mass ejections (CMEs) remains controversial. One of the leading theories is magnetic breakout, in which magnetic reconnection occurring high in the corona removes the confinement on an energized low-corona structure from the overlying magnetic field, thus allowing it to erupt. Here, we report critical observational evidence of this elusive breakout reconnection in a multi-polar magnetic configuration that leads to a CME and an X-class, long-duration flare. Its occurrence is supported by the presence of pairs of heated cusp-shaped loops around an X-type null point and signatures of reconnection inflows. Other peculiar features new to the breakout picture include sequential loop brightening, coronal hard X-rays at energies up to ∼100 keV, and extended high-corona X-rays above the later restored multi-polar structure. These observations, from a novel perspective with clarity never achieved before, present crucial clues to understanding the initiation mechanism of solar eruptions.

EmployingSolar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) multi-wavelength images, we report the coronal condensation during the magnetic reconnection (MR) between a system of open and closed coronal loops. Higher-lying magnetically open structures, observed in AIA 171 Å images above the solar limb, move downward and interact with the lower-lying closed loops, resulting in the formation of dips in the former. An X-type structure forms at the interface. The interacting loops reconnect and disappear. Two sets of newly reconnected loops then form and recede from the MR region. During the MR process, bright emission appears sequentially in the AIA 131 and 304 Å channels repeatedly in the dips of higher-lying open structures. This indicates the cooling and condensation process of hotter plasma from ∼0.9 MK down to ∼0.6 MK, and then to ∼0.05 MK, also supported by the light curves of the AIA 171, 131, and 304 Å channels. The part of higher-lying open structures supporting the condensation participate in the successive MR. Without support from underlying loops, the condensation then rains back to the solar surface along the newly reconnected loops. Our results suggest that the MR between coronal loops leads to the condensation of hotter coronal plasma and its downflows. MR thus plays an active role in the mass cycle of coronal plasma because it can initiate the catastrophic cooling and condensation. This underlines that the magnetic and thermal evolution has to be treated together and cannot be separated, even in the case of catastrophic cooling.

Employing Solar Dynamics Observatory /Atmospheric Imaging Assembly (AIA) multi-wavelength images, we have presented coronal condensations caused by magnetic reconnection between a system of open and closed solar coronal loops. In this Letter, we report the quasi-periodic fast magnetoacoustic waves propagating away from the reconnection region upward across the higher-lying open loops during the reconnection process. On 2012 January 19, reconnection between the higher-lying open loops and lower-lying closed loops took place, and two sets of newly reconnected loops formed. Thereafter, cooling and condensations of coronal plasma occurred in the magnetic dip region of higher-lying open loops. During the reconnection process, disturbances originating from the reconnection region propagate upward across the magnetic dip region of higher-lying loops with the mean speed and mean speed amplitude of 200 and 30 km s ⁻¹ , respectively. The mean speed of the propagating disturbances decreases from ∼230 km s ⁻¹ to ∼150 km s ⁻¹ during the coronal condensation process, and then increases to ∼220 km s ⁻¹ . This temporal evolution of the mean speed anti-correlates with the light curves of the AIA 131 and 304 Å channels that show the cooling and condensation process of coronal plasma. Furthermore, the propagating disturbances appear quasi-periodically with a peak period of 4 minutes. Our results suggest that the disturbances represent the quasi-periodic fast propagating magnetoacoustic (QFPM) waves originating from the magnetic reconnection between coronal loops.

Solar filaments/prominences are one of the most common features in the corona, which may lead to energetic coronal mass ejections (CMEs) and flares when they erupt. Filaments are about 100 times cooler and denser than the coronal material, and physical understanding of their material origin remains controversial. Two types of scenarios have been proposed: one argues that the filament plasma is brought into the corona from photosphere or chromosphere through a siphon or evaporation/injection process, while the other suggests that the material condenses from the surrounding coronal plasma due to thermal instability. The elemental abundance analysis is a reasonable clue to constrain the models, as the siphon or evaporation/injection model would predict that the filament material abundances are close to the photospheric or chromospheric ones, while the condensation model should have coronal abundances. In this Letter, we analyze the elemental abundances of a magnetic cloud that contains the ejected filament material. The corresponding filament eruption occurred on 1998 April 29, accompanying an M6.8 class soft X-ray flare located at the heliographic coordinates S18E20 (NOAA 08210) and a fast halo CME with the linear velocity of 1374 km s⁻¹ near the Sun. We find that the abundance ratios of elements with low and high first ionization potential such as Fe/O, Mg/O, and Si/O are 0.150, 0.050, and 0.070, respectively, approaching their corresponding photospheric values 0.065, 0.081, and 0.066, which does not support the coronal origin of the filament plasma.

Magnetic clouds (MCs) are the interplanetary counterparts of coronal magnetic flux ropes. They can provide valuable information regarding flux rope characteristics at their eruption stage in the corona, which is unable to be explored in situ at present. In this paper, we make a comprehensive survey of the average iron charge-state ( ) distributions inside 96 MCs for solar cycle 23 using Advanced Composition Explorer (ACE) data. Since the in the solar wind are typically around 9+ to 11+, the Fe charge state is defined as being high when the is larger than 12+, which implies the existence of a considerable amount of Fe ions with high charge states (e.g., ≥16+). The statistical results show that the distributions of 92 (∼96%) MCs can be classified into four groups with different characteristics. In group A (11 MCs), the shows a bi-modal distribution with both peaks being higher than 12+. Group B (4 MCs) presents a unimodal distribution of , with its peak being higher than 12+. In groups C (29 MCs) and D (48 MCs), the remains higher and lower than 12+ throughout ACE’s passage through the MC, respectively. Possible explanations of these distributions are discussed.