An Extreme Ultraviolet (EUV) jet that occurred around 22:30 on July 2, 2012 was observed by the Atmospheric Imaging Assembly (AIA) on-board the Solar Dynamics Observatory (SDO). There were two phases of the jet. In Phase 1, two blobs were observed. In Phase 2, the intensity of the jet was almost coherent initially. One minute later, three blobs were formed at the same time in the jet, and the width of the jet changed after the formation of these blobs. The formation and evolution processes of the blobs in these two phases are analyzed in this paper. The physical parameters of the blobs are determined. The measured width of the blobs is 0.8 − 2.3 Mm, and the apparent velocities of the blobs are from 59 km s⁻¹ to 185 km s⁻¹. The formation mechanism of the blobs is likely to be tear-mode instability.

Jets often occur repeatedly from almost the same location. In this paper, a complex solar jet was observed with two phases to the west of NOAA AR 11513 on 2012 July 2. If it had been observed at only moderate resolution, the two phases and their points of origin would have been regarded as identical. However, at high resolution we find that the two phases merge into one another and the accompanying footpoint brightenings occur at different locations. The phases originate from different magnetic patches rather than being one phase originating from the same patch. Photospheric line of sight (LOS) magnetograms show that the bases of the two phases lie in two different patches of magnetic flux that decrease in size during the occurrence of the two phases. Based on these observations, we suggest that the driving mechanism of the two successive phases is magnetic cancellation of two separate magnetic fragments with an opposite-polarity fragment between them.

Multiwavelength observations of a prominence eruption provide an opportunity to uncover the physical mechanism of the triggering and the evolution process of the eruption. In this paper, we investigate a prominence that erupted on 2012 October 14, recorded in Hα, EUV, and X-ray wavelengths. The process of the eruption gives evidence for the existence of a helical magnetic structure showing the twist converting to writhe. The estimated twist is (three turns), exceeding the threshold of the kink instability. The rising plasma reached a high speed of 228 km s⁻¹, followed by a sudden rapid acceleration of 2715 m s⁻², and was synchronous with a solar flare. Co-spatial cusp-shaped structures were observed in both 131 and 94 Å images from the Atmospheric Imaging Assembly, signifying the location of the magnetic reconnection. The erupted flux rope finally underwent a deceleration with a maximum value of 391 m s⁻², which is larger than the freefall acceleration on the Sun (273 m s⁻²), suggesting that the eruption finally failed, possibly due to an inward magnetic tension force.

We present an analysis of the formation and eruption of a filament and fast coronal mass ejection associated with a flare that occurred in active region 11429 using observations in the ultraviolet, extreme ultraviolet, X-ray, and radio wavelength bands. Precursor activity began as an interaction between two filaments, F1 and F2, that are identified as having twisted magnetic flux ropes (MFRs). Transient brightenings in all wavelengths are observed as a result of this interaction, likely the result of magnetic reconnection between the two filaments. This interaction results in a reconfiguration of the two filaments into a long overlying filament and a shorter low-lying filament. The upper filament subsequently undergoes a partial confined eruption. Plasma flows originating near the east footpoint of F1 lead to an extension of the upper filament into the filament channel to the west, resulting in a new active region filament (ARF). This new filament begins a slow rise and expansion. During its slowly rising phase, the MFR in which the filament is embedded becomes visible, with both the filament and flux rope rising and expanding simultaneously. The twist of the magnetic rope is determined as four turns. The erupting configuration changes from a twisted arch shape to a reversed γ shape within ∼75 s at the beginning of the fast-rise phase, representing a transformation from twist to writhe. The observations provide a clear example of filament formation via the tether-cutting reconnection of two nearby filaments. A helical kink instability may be the trigger of the ARF eruption.