Jiangtao Su

SYMPATHETIC PARTIAL AND FULL FILAMENT ERUPTIONS OBSERVED IN ONE SOLAR BREAKOUT EVENT

We report two sympathetic solar eruptions including a partial and a full flux rope eruption in a quadrupolar magnetic region where a large and a small filament resided above the middle and the east neutral lines, respectively. The large filament first rose slowly at a speed of 8 km s(-1) for 23 minutes; it then accelerated to 102 km s(-1). Finally, this filament erupted successfully and caused a coronal mass ejection. During the slow rising phase, various evidence for breakout-like external reconnection has been identified at high and low temperature lines. The eruption of the small filament started around the end of the large filaments slow rising. This filament erupted partially, and no associated coronal mass ejection could be detected. Based on a potential field extrapolation, we find that the topology of the three-dimensional coronal field above the source region is composed of three low-lying lobes and a large overlying flux system, and a null point located between the middle lobe and the overlying antiparallel flux system. We propose a possible mechanism within the framework of the magnetic breakout model to interpret the sympathetic filament eruptions, in which the magnetic implosion mechanism is thought to be a possible link between the sympathetic eruptions, and the external reconnection at the null point transfers field lines from the middle lobe to the lateral lobes and thereby leads to the full (partial) eruption of the observed large (small) filament. Other possible mechanisms are also discussed briefly. We conclude that the structural properties of coronal fields are important for producing sympathetic eruptions.

ON A CORONAL BLOWOUT JET: THE FIRST OBSERVATION OF A SIMULTANEOUSLY PRODUCED BUBBLE-LIKE CME AND A JET-LIKE CME IN A SOLAR EVENT

The coronal blowout jet is a peculiar category among various jet phenomena, in which the sheared base arch, often carrying a small filament, experiences a miniature version of blowout eruption that produces large-scale coronal mass ejection (CME). In this paper, we report such a coronal blowout jet with high-resolution multi-wavelength and multi-angle observations taken from Solar Dynamics Observatory, Solar Terrestrial Relations Observatory, and Big Bear Solar Observatory. For the first time, we find that simultaneous bubble-like and jet-like CMEs were dynamically related to the blowout jet that showed cool and hot components next to each other. Our observational results indicate that (1) the cool component resulted from the eruption of the filament contained within the jets base arch, and it further caused the bubble-like CME; (2) the jet-like CME was associated with the hot component, which was the outward moving heated plasma generated by the reconnection of the base arch and its ambient open field lines. On the other hand, bifurcation of the jets cool component was also observed, which resulted from the uncoupling of the erupting filaments two legs that were highly twisted at the very beginning. Based on these results, we propose a model to interpret the coronal blowout jet, in which the external reconnection not only produces the jet-like CME, but also leads to the rising of the filament. Subsequently, internal reconnection starts underneath the rising filament and thereby causes the bubble-like CME.

KINEMATICS AND FINE STRUCTURE OF AN UNWINDING POLAR JET OBSERVED BY THE SOLAR DYNAMIC OBSERVATORY/ATMOSPHERIC IMAGING ASSEMBLY

We present an observational study of the kinematics and fine structure of an unwinding polar jet, with high temporal and spatial observations taken by the Atmospheric Imaging Assembly on board the Solar Dynamic Observatory and the Solar Magnetic Activity Research Telescope. During the rising period, the shape of the jet resembled a cylinder with helical structures on the surface, while the mass of the jet was mainly distributed on the cylinders shell. In the radial direction, the jet expanded successively at its western side and underwent three distinct phases: the gradually expanding phase, the fast expanding phase, and the steady phase. Each phase lasted for about 12 minutes. The angular speed of the unwinding motion of the jet and the twist transferred into the outer corona during the eruption are estimated to be 11.1 x 10(-3) rad s(-1) (period = 564 s) and 1.17-2.55 turns (or 2.34-5.1 pi), respectively. On the other hand, by calculating the azimuthal component of the magnetic field in the jet and comparing the free energy stored in the non-potential magnetic field with the jets total energy, we find that the non-potential magnetic field in the jet is enough to supply the energy for the ejection. These new observational results strongly support the scenario that the jets are driven by the magnetic twist, which is stored in the twisted closed field of a small bipole, and released through magnetic reconnection between the bipole and its ambient open field.

Imaging Observations of Quasi-periodic Pulsations in Solar Flare Loops with SDO/AIA

Quasi-periodic pulsations (QPPs) of flaring emission with periods from a few seconds to tens of minutes have been widely detected from radio bands to gamma-ray emissions. However, in the past the spatial information of pulsations could not be utilized well due to the instrument limits. We report here imaging observations of the QPPs in three loop sections during a C1.7 flare with periods of P = 24 s-3 minutes by means of the extreme-ultraviolet 171 angstrom channel of the Atmospheric Imaging Assembly (AIA) instrument on board the Solar Dynamics Observatory. We confirm that the QPPs with the shortest period of 24 s were not of an artifact produced by the Nyquist frequency of the AIA 12 s cadence. The QPPs in the three loop sections were interconnected and closely associated with the flare. The detected perturbations propagated along the loops at speeds of 65-200 km s(-1), close to those of acoustic waves in them. The loops were made up of many bright blobs arranged in alternating bright and dark changes in intensity (spatial periodical distribution) with the wavelengths 2.4-5 Mm (as if they were magnetohydrodynamic waves). Furthermore, in the time-distance diagrams, the detected perturbation wavelengths of the QPPs are estimated to be similar to 10 Mm, which evidently do not fit the above ones of the spatial periodic distributions and produce a difference of a factor of 2-4 with them. It is suggested that the short QPPs with periods P 60 s were the higher (e. g., > 2nd) harmonics of slow magnetoacoustic waves.

OSCILLATIONS IN A SUNSPOT WITH LIGHT BRIDGES

The Solar Optical Telescope on board Hinode observed a sunspot (AR 11836) with two light bridges (LBs) on 2013 August 31. We analyzed a two-hour Ca II H emission intensity data set and detected strong five-minute oscillation power on both LBs and in the inner penumbra. The time-distance plot reveals that the five-minute oscillation phase does not vary significantly along the thin bridge, indicating that the oscillations are likely to originate from underneath it. The slit taken along the central axis of the wide LB exhibits a standing wave feature. However, at the center of the wide bridge, the five-minute oscillation power is found to be stronger than at its sides. Moreover, the time-distance plot across the wide bridge exhibits a herringbone pattern that indicates a counter-stream of two running waves, which originated at the bridges sides. Thus, the five-minute oscillations on the wide bridge also resemble the properties of running penumbral waves. The five-minute oscillations are suppressed in the umbra, while the three-minute oscillations occupy all three cores of the sunspots umbra, separated by the LBs. The three-minute oscillations were found to be in phase at both sides of the LBs. This may indicate that either LBs do not affect umbral oscillations, or that umbral oscillations at different umbral cores share the same source. It also indicates that LBs are rather shallow objects situated in the upper part of the umbra. We found that umbral flashes (UFs) follow the life cycles of umbral oscillations with much larger amplitudes. They cannot propagate across LBs. UFs dominate the three-minute oscillation power within each core; however, they do not disrupt the phase of umbral oscillation.

Recurrent solar jets induced by a satellite spot and moving magnetic features

Recurrent and homologous jets were observed to the west edge of active region NOAA 11513 at the boundary of a coronal hole. We find two kinds of cancellations between opposite polarity magnetic fluxes, inducing the generation of recurrent jets. First, a satellite spot continuously collides with a pre-existing opposite polarity magnetic field and causes recurrent solar jets. Second, moving magnetic features, which emerge near the sunspot penumbra, pass through the ambient plasma and eventually collide with the opposite polarity magnetic field. Among these recurrent jets, a blowout jet that occurred around 21:10 UT is investigated. The rotation of the pre-existing magnetic field and the shear motion of the satellite spot accumulate magnetic energy, which creates the possibility for the jet to experience blowout right from the standard.

A SOLAR ERUPTION DRIVEN BY RAPID SUNSPOT ROTATION

We present the observation of a major solar eruption that is associated with fast sunspot rotation. The event includes a sigmoidal filament eruption, a coronal mass ejection, and a GOES X2.1 flare from NOAA active region 11283. The filament and some overlying arcades were partially rooted in a sunspot. The sunspot rotated at

LOCAL TWIST AND CURRENT HELICITY DISTRIBUTIONS OF ACTIVE REGION NOAA 10930

\sim

OBSERVATIONAL EVIDENCE OF CHANGING PHOTOSPHERIC VECTOR MAGNETIC FIELDS ASSOCIATED WITH SOLAR FLARES

10

A FLUX ROPE ERUPTION TRIGGERED BY JETS

^\circ