Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userAcceleration phases of a solar filament during its eruption
127
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
Filament eruptions often lead to coronal mass ejections (CMEs), which can affect critical technological systems in space and on the ground when they interact with the geo-magnetosphere in high speeds. Therefore, it is an important issue to investigate the acceleration mechanisms of CMEs in solar/space physics. Based on observations and simulations, the resistive magnetic reconnection and the ideal instability of magnetic flux rope have been proposed to accelerate CMEs. However, it remains elusive whether both of them play a comparable role during a particular eruption. It has been extremely difficult to separate their contributions as they often work in a close time sequence during one fast acceleration phase. Here we report an intriguing filament eruption event, which shows two apparently separated fast acceleration phases and provides us an excellent opportunity to address the issue. Through analyzing the correlations between velocity (acceleration) and soft (hard) X-ray profiles, we suggest that the instability and magnetic reconnection make a major contribution during the first and second fast acceleration phases, respectively. Further, we find that both processes have a comparable contribution to accelerate the filament in this event.
rate research
Read More
We investigate the dynamics and magnetic properties of the plasma, such as line-of-sight velocity (LOS), optical depth, vertical and horizontal magnetic fields, belonging to an erupted solar filament. The filament eruption was observed with the GREGOR Infrared Spectrograph (GRIS) at the 1.5-meter GREGOR telescope on 2016 July 3. Three consecutive full-Stokes slit-spectropolarimetric scans in the He I 10830 r{A} spectral range were acquired. The Stokes I profiles were classified using the machine learning k-means algorithm and then inverted with different initial conditions using the HAZEL code. The erupting-filament material presents the following physical conditions: (1) ubiquitous upward motions with peak LOS velocities of ~73 km/s; (2) predominant large horizontal components of the magnetic field, on average, in the range of 173-254 G, whereas the vertical components of the fields are much lower, on average between 39-58 G; (3) optical depths in the range of 0.7-1.1. The average azimuth orientation of the field lines between two consecutive raster scans (<2.5 minutes) remained constant. The analyzed filament eruption belonged to the fast rising phase, with total velocities of about 124 km/s. The orientation of the magnetic field lines does not change from one raster scan to the other, indicating that the untwisting phase has not started yet. The untwisting seems to start about 15 min after the beginning of the filament eruption.
Solar filaments often erupt partially. Although how they split remains elusive, the splitting process has the potential of revealing the filament structure and eruption mechanism. Here we investigate the pre-eruption splitting of an apparently single filament and its subsequent partial eruption on 2012 September 27. The evolution is characterized by three stages with distinct dynamics. During the quasi-static stage, the splitting proceeds gradually for about 1.5 hrs, with the upper branch rising at a few kilometers per second and displaying swirling motions about its axis. During the precursor stage that lasts for about 10 min, the upper branch rises at tens of kilometers per second, with a pair of conjugated dimming regions starting to develop at its footpoints; with the swirling motions turning chaotic, the axis of the upper branch whips southward, which drives an arc-shaped EUV front propagating in the similar direction. During the eruption stage, the upper branch erupts with the onset of a C3.7-class two-ribbon flare, while the lower branch remains stable. Judging from the well separated footpoints of the upper branch from those of the lower one, we suggest that the pre-eruption filament processes a double-decker structure composed of two distinct flux bundles, whose formation is associated with gradual magnetic flux cancellations and converging photospheric flows around the polarity inversion line.
The sun occasionally undergoes the so-called grand minima, in which its magnetic activity, measured by the number of sunspots, is suppressed for decades. The most prominent grand minima, since the beginning of telescopic observations of sunspots, is the Maunder minimum (1645-1715), when the sunspots became rather scarce. The mechanism underlying the grand minima remains poorly understood as there is little observational information of the solar magnetic field at that time. In this study, we examine the records of one candidate aurora display in China and Japan during the Maunder minimum. The presence of auroras in such mid magnetic latitudes indicates the occurrence of great geomagnetic storms that are usually produced by strong solar flares. However, the records of contemporary sunspot observations from Europe suggest that, at least for the likely aurora event, there was no large sunspot that could produce a strong flare. Through simple theoretical arguments, we show that this geomagnetic storm could have been generated by an eruption giant quiescent filament, or a series of such events.
We analyze multi-wavelength and multi-viewpoint observations of a helically twisted plasma jet formed during a confined filament eruption on 10-11 April 2013. Given a rather large scale event with its high spatial and temporal resolution observations, it allows us to clearly understand some new physical details about the formation and triggering mechanism of twisting jet. We identify a pre-existing flux rope associated with a sinistral filament, which was observed several days before the event. The confined eruption of the filament within a null point topology, also known as an Eiffel tower (or inverted-Y) magnetic field configuration results in the formation of a twisted jet after the magnetic reconnection near a null point. The sign of helicity in the jet is found to be the same as that of the sign of helicity in the filament. Untwisting motion of the reconnected magnetic field lines gives rise to the accelerating plasma along the jet axis. The event clearly shows the twist injection from the pre-eruptive magnetic field to the jet.
We study a sequence of eruptive events including filament eruption, a GOES C4.3 flare and a coronal mass ejection. We aim to identify the possible trigger(s) and precursor(s) of the filament destabilisation; investigate flare kernel characteristics; flare ribbons/kernels formation and evolution; study the interrelation of the filament-eruption/flare/coronal-mass-ejection phenomena as part of the integral active-region magnetic field configuration; determine Halpha line profile evolution during the eruptive phenomena. Multi-instrument observations are analysed including Halpha line profiles, speckle images at Halpha-0.8 AA and Halpha+0.8 AA from IBIS at DST/NSO, EUV images and magnetograms from the SDO, coronagraph images from STEREO and the X-ray flux observations from FERMI and GOES. We establish that the filament destabilisation and eruption are the main trigger for the flaring activity. A surge-like event with a circular ribbon in one of the filament footpoints is determined as the possible trigger of the filament destabilisation. Plasma draining in this footpoint is identified as the precursor for the filament eruption. A magnetic flux emergence prior to the filament destabilisation followed by a high rate of flux cancelation of 1.34$times10^{16}$ Mx s$^{-1}$ is found during the flare activity. The flare X-ray lightcurves reveal three phases that are found to be associated with three different ribbons occurring consecutively. A kernel from each ribbon is selected and analysed. The kernel lightcurves and H alpha line profiles reveal that the emission increase in the line centre is stronger than that in the line wings. A delay of around 5-6 mins is found between the increase in the line centre and the occurrence of red asymmetry. Only red asymmetry is observed in the ribbons during the impulsive phases. Blue asymmetry is only associated with the dynamic filament.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
