scholarly journals Shearing motions and torus instability in the 2010 April 3 filament eruption

2013 ◽  
Vol 8 (S300) ◽  
pp. 475-476
Author(s):  
F. P. Zuccarello ◽  
P. Romano ◽  
F. Zuccarello ◽  
S. Poedts
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Flux Rope ◽  
Active Region Noaa ◽  
Axial Field ◽  
Drift Motion ◽  
Filament Eruption ◽  
Onset Condition ◽  
Mass Ejection ◽  
The Magnetic Field

AbstractThe magnetic field evolution of active region NOAA 11059 is studied in order to determine the possible causes and mechanisms that led to the initiation of the 2010 April 3 coronal mass ejection (CME).We find (1) that the magnetic configuration of the active region is unstable to the torus instability and (2) that persistent shearing motions characterized the negative polarity, resulting in a southward, almost parallel to the meridians, drift motion of the negative magnetic field concentrations.We conclude that these shearing motions increased the axial field of the filament eventually bringing the flux rope axis to a height where the onset condition for the torus instability was satisfied.

scholarly journals The exceptional aspects of the confined X-class flares of solar active region 2192

2015 ◽  
Vol 11 (S320) ◽  
pp. 60-63
Author(s):  
Julia K. Thalmann ◽  
Yang Su ◽  
Manuela Temmer ◽  
Astrid M. Veronig
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Active Region Noaa ◽  
High Energies ◽  
The Past ◽  
Large Scale Magnetic Field ◽  
High Level ◽  
Mass Ejection

AbstractDuring late October 2014, active region NOAA 2192 caused an unusual high level of solar activity, within an otherwise weak solar cycle. While crossing the solar disk, during a period of 11 days, it was the source of 114 flares of GOES class C1.0 and larger, including 29 M- and 6 X-flares. Surprisingly, none of the major flares (GOES class M5.0 and larger) was accompanied by a coronal mass ejection, contrary to statistical tendencies found in the past. From modeling the coronal magnetic field of NOAA 2192 and its surrounding, we suspect that the cause of the confined character of the flares is the strong surrounding and overlying large-scale magnetic field. Furthermore, we find evidence for multiple magnetic reconnection processes within a single flare, during which electrons were accelerated to unusual high energies.

scholarly journals Reconstruction of the Coronal Magnetic Field for Active Region NOAA 8151

2001 ◽  
Vol 203 ◽  
pp. 441-443
Author(s):  
S. Régnier ◽  
T. Amari
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Magnetic Energy ◽  
Coronal Magnetic Field ◽  
X Rays ◽  
Active Region Noaa ◽  
Filament Eruption ◽  
Linear Force ◽  
Region Noaa ◽  
Field Lines

The active region NOAA 8151 observed between February 11–13, 1998 exhibits a filament eruption linked to the disappearance of a sigmoidal structure. Using vector magnetograms from IVM (Mees Observatory, Hawaii), we perform a non linear force-free reconstruction of the coronal magnetic field above this active region. This reconstruction allows to determine the distribution of electric currents, the magnetic energy and the relative magnetic helicity. The reconstructed magnetic field lines are compared to the soft X-rays (SXT, Yohkoh) observations.

scholarly journals Searching for failed eruptions interacting with overlying magnetic field

2015 ◽  
Vol 11 (S320) ◽  
pp. 221-223 ◽  
Author(s):  
Dominik Gronkiewicz ◽  
Tomasz Mrozek ◽  
Sylwester Kołomański ◽  
Martyna Chruślińska
Keyword(s):  
Magnetic Field ◽  
Statistical Analysis ◽  
Active Region ◽  
Solar Flares ◽  
Active Regions ◽  
Automated Method ◽  
Solar Eruptions ◽  
Mass Ejection ◽  
The Magnetic Field ◽  
Flare Site

AbstractIt is well known that not all solar flares are connected with eruptions followed by coronal mass ejection (CME). Even strongest X-class flares may not be accompanied by eruptions or are accompanied by failed eruptions. One of important factor that prevent eruption from developing into CME is strength of the magnetic field overlying flare site. Few observations show that active regions with specific magnetic configuration may produce many CME-less solar flares. Therefore, forecasts of geoeffective events based on active region properties have to take into account probability of confining solar eruptions. Present observations of SDO/AIA give a chance for deep statistical analysis of properties of an active region which may lead to confining an eruption. We developed automated method which can recognize eruptions in AIA images. With this tool we will be able to analyze statistical properties of failed eruptions observed by AIA telescope.

scholarly journals Polarisation and source structure of solar stationary type IV radio bursts

2020 ◽  
Vol 639 ◽  
pp. A102 ◽  
Author(s):  
Carolina Salas-Matamoros ◽  
Karl-Ludwig Klein
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Radio Emission ◽  
Flux Rope ◽  
Field Orientation ◽  
Type Iv ◽  
Gradual Disappearance ◽  
Stationary Type ◽  
Source Structure ◽  
The Magnetic Field

The reconfiguration of the magnetic field during and after a coronal mass ejection (CME) may be accompanied by radio emission from non-thermal electrons. In particular, stationary type IV bursts (also called storm continua) are emitted by electrons in closed magnetic configurations usually located in the wake of the outward-travelling CME. Although stationary type IV bursts, which stand out by their long duration (up to several hours) and strong circular polarisation, have been known for more than fifty years, there have been no systematic studies since the 1980s. In this work we use the data pool of the Nançay Radioheliograph together with white-light coronagraphy, EUV imaging and magnetography from the SoHO, Proba2, SDO and STEREO spacecraft to revisit the source structure and polarisation of a sample of seven well-defined stationary type IV bursts at decimetre-to-metre wavelengths. The radio sources are most often found in one leg, in one case both legs, of the magnetic flux rope erupting into the high corona during the CME. The cross-correlation of the brightness temperature time profiles in the event with sources in both legs implies that the radiating electrons have energies of a few tens of keV. Comparison with the magnetic field measured in the photosphere and its potential extrapolation into the corona shows that the radio emission is in the ordinary mode. This result was inferred historically by means of the hypothesis that the magnetic field orientation in the radio source was that of the dominant sunspot in the parent active region. This hypothesis is shown here to be in conflict with noise storms in the same active region. It is confirmed that the polarisation of stationary type IV continua may be strong, but is rarely total, and that it gradually increases in the early phase of the radio event. We find that the increase is related to the gradual disappearance of some weakly polarised or unpolarised substructure, which dominates the first minutes of the radio emission.

scholarly journals Numerical simulation of helical jets at active region peripheries

2019 ◽  
Vol 490 (3) ◽  
pp. 3679-3690 ◽  
Author(s):  
Peter F Wyper ◽  
C Richard DeVore ◽  
Spiro K Antiochos
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Three Dimensional ◽  
Flux Rope ◽  
Active Regions ◽  
Quantitative Agreement ◽  
Null Point ◽  
Closed Field ◽  
The Magnetic Field ◽  
Bald Patch

ABSTRACT Coronal jets are observed above minority-polarity intrusions throughout the solar corona. Some of the most energetic ones occur on the periphery of active regions where the magnetic field is strongly inclined. These jets exhibit a non-radial propagation in the low corona as they follow the inclined field, and often have a broad, helical shape. We present a three-dimensional magnetohydrodynamic simulation of such an active-region-periphery helical jet. We consider an initially potential field with a bipolar flux distribution embedded in a highly inclined magnetic field, representative of the field nearby an active region. The flux of the minority polarity sits below a bald-patch separatrix initially. Surface motions are used to inject free energy into the closed field beneath the separatrix, forming a sigmoidal flux rope that eventually erupts producing a helical jet. We find that a null point replaces the bald patch early in the evolution and that the eruption results from a combination of magnetic breakout and an ideal kinking of the erupting flux rope. We discuss how the two mechanisms are coupled, and compare our results with previous simulations of coronal-hole jets. This comparison supports the hypothesis that the generic mechanism for all coronal jets is a coupling between breakout reconnection and an ideal instability. We further show that our results are in good qualitative and quantitative agreement with observations of active-region-periphery jets.

Effects of optimisation parameters on data-driven magnetofrictional modelling 

2021 ◽  
Author(s):  
Anshu Kumari ◽  
Daniel Price ◽  
Emilia Kilpua ◽  
Jens Pomoell ◽  
Farhad Daei
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Large Scale ◽  
Magnetic Energy ◽  
Flux Rope ◽  
Coronal Magnetic Field ◽  
Early Evolution ◽  
Data Driven ◽  
Magnetic Field Magnitude ◽  
Mass Ejection

<p>The solar coronal magnetic field plays an important role in the formation, evolution, and dynamics of small and large-scale structures in the corona. Estimation of the coronal magnetic field, the ultimate driver of space weather, particularly in the ‘low’ and ‘middle’ corona, is presently limited due to practical difficulties. Data-driven time-dependent magnetofrictional modelling (TMFM) of active region magnetic fields has been proven as a tool to observe and study the corona. In this work, we present a detailed study of data-driven TMFM of active region 12473 to trace the early evolution of the flux rope related to the coronal mass ejection that occurred on 28 December 2015. Non-inductive electric field component in the photosphere is critical for energizing and introducing twist to the coronal magnetic field, thereby allowing unstable configurations to be formed. We estimate this component using an approach based on optimizing the injection of magnetic energy. We study the effects of these optimisation parameters on the data driven coronal simulations. By varying the free optimisation parameters, we explore the changes in flux rope formation and their early evolution, as well other parameters, e.g. axial flux, magnetic field magnitude.</p>

scholarly journals SIGNIFICANT INHOMOGENEITY OF A MAGNETIC FIELD IN THE GREATEST SUNSPOT OF ACTIVE REGION NOAA 10488

2019 ◽  
pp. 12-16
Author(s):  
V. Lozitsky
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Visible Region ◽  
Spectral Lines ◽  
Homogeneous Field ◽  
Active Region Noaa ◽  
Component Structure ◽  
Wide Range ◽  
Region Noaa ◽  
The Magnetic Field

The main conclusion of our work is that in the greatest sunspot of the active region NOAA 10488 there was a large dispersion of magnetic field strengths, at which the minimum and maximum strengths differed by approximately an order of magnitude. This result applies to the central part of the sunspot umbra, for a square with sides 2 × 2 Mm2 in the picture plane. Observation material was obtained on the Echelle spectrograph of the horizontal solar telescope of the Astronomical Observatory of Taras Shevchenko National University of Kyiv. This instrument allows to analyze the Zeeman effect simultaneously in thousands of spectral lines of almost the entire visible region of the spectrum. For our analysis, four iron FeI lines with wavelengths of 6290.97, 6301.51, 6302.50 and 6498.97 Ǻ and effective Lande factors 1.481, 1.669, 2.487 and 1.375, respectively, were used. In the studied sunspot, only FeI 6302.5 from these lines has a complete Zeeman splitting, which corresponds to magnetic field of 3400 G. However, the splitting of the other three lines corresponds to magnetic fields in a very wide range, from several hundred Gauss to 3700 G, which indicates significant inhomogeneity of the magnetic field. Also, the shape of bisectors of I ± V profiles does not correspond to a case of homogeneous field. In particular, theoretically, in a homogeneous and non-longitudinal magnetic field, bisectors should be have the maximum splitting in the nuclei of these lines, whereas in reality the picture is more complicated. All three of these lines show a tendency to increase splitting in distant wings, at distances of 120-250 mAh from their centers. This effect is possible under the two-component structure of the magnetic field (background field + spatially unresolved structures) having magnetic strengths in the range of 4.5-8 kGs in spatially unresolved structures. Magnetic polarity in both components is the same, namely N. The observational data indicate that the magnetic field value differed significantly not only on the surface, but also in height in the studied sunspot.

scholarly journals Toroidal models of magnetic field with twisted structure

2019 ◽  
Vol 5 (2) ◽  
pp. 69-75 ◽  
Author(s):  
Анастасия Петухова ◽  
Anastasia Petukhova ◽  
Станислав Петухов ◽  
Stanislav Petukhov
Keyword(s):  
Magnetic Field ◽  
Flux Rope ◽  
Forbush Decrease ◽  
Magnetic Clouds ◽  
Integral Model ◽  
Model Parameters ◽  
Magnetic Field Region ◽  
Transport Effects ◽  
Mass Ejection ◽  
The Magnetic Field

We present and discuss properties of the following magnetic field models in a magnetic cloud: Miller and Turner solution, modified Miller–Turner solution, Romashets–Vandas toroidal and integral models, and Krittinatham–Ruffolo model. Helicity of the magnetic field in all the models is the main feature of magnetic clouds. The first three models describe the magnetic field inside an ideal torus. In the integral model, parameters of a generating torus ambiguously determine the volume and form of the magnetic field region. In the Krittinatham–Ruffolo model, the cross-section radius of the torus is variable, thereby it corresponds more closely to the real form of magnetic clouds in the inner heliosphere. These models can be used to interpret in-situ observations of the magnetic flux rope, to study a Forbush decrease in magnetic clouds and transport effects of solar energetic particles injected into a coronal mass ejection.

scholarly journals A filament supported by different magnetic field configurations

2010 ◽  
Vol 6 (S273) ◽  
pp. 328-332
Author(s):  
Y. Guo ◽  
B. Schmieder ◽  
P. Démoulin ◽  
T. Wiegelmann ◽  
G. Aulanier ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Magnetic Cloud ◽  
Flux Rope ◽  
The Other ◽  
Axial Field ◽  
New Finding ◽  
Nonlinear Force ◽  
Simultaneous Existence ◽  
Magnetogram Data

AbstractA nonlinear force-free magnetic field extrapolation of vector magnetogram data obtained by THEMIS/MTR on 2005 May 27 suggests the simultaneous existence of different magnetic configurations within one active region filament: one part of the filament is supported by field line dips within a flux rope, while the other part is located in dips within an arcade structure. Although the axial field chirality (dextral) and the magnetic helicity (negative) are the same along the whole filament, the chiralities of the filament barbs at different sections are opposite, i.e., right-bearing in the flux rope part and left-bearing in the arcade part. This argues against past suggestions that different barb chiralities imply different signs of helicity of the underlying magnetic field. This new finding about the chirality of filaments will be useful to associate eruptive filaments and magnetic cloud using the helicity parameter in the Space Weather Science.

scholarly journals Full Stokes observations in the He i 1083 nm spectral region covering an M3.2 flare

2014 ◽  
Vol 10 (S305) ◽  
pp. 73-78 ◽  
Author(s):  
Christoph Kuckein ◽  
Manuel Collados ◽  
Rafael Manso Sainz ◽  
Andrés Asensio Ramos
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Field Strength ◽  
Spectral Region ◽  
Active Region Noaa ◽  
Vacuum Tower ◽  
Data Set ◽  
Blue Component ◽  
Spectral Line Profile ◽  
The Magnetic Field

AbstractWe present an exceptional data set acquired with the Vacuum Tower Telescope (Tenerife, Spain) covering the pre-flare, flare, and post-flare stages of an M3.2 flare. The full Stokes spectropolarimetric observations were recorded with the Tenerife Infrared Polarimeter in the He i 1083.0 nm spectral region. The object under study was active region NOAA 11748 on 2013 May 17. During the flare the chomospheric He i 1083.0 nm intensity goes strongly into emission. However, the nearby photospheric Si i 1082.7 nm spectral line profile only gets shallower and stays in absorption. Linear polarization (Stokes Q and U) is detected in all lines of the He i triplet during the flare. Moreover, the circular polarization (Stokes V) is dominant during the flare, being the blue component of the He i triplet much stronger than the red component, and both are stronger than the Si i Stokes V profile. The Si i inversions reveal enormous changes of the photospheric magnetic field during the flare. Before the flare magnetic field concentrations of up to ~1500 G are inferred. During the flare the magnetic field strength globally decreases and in some cases it is even absent. After the flare the magnetic field recovers its strength and initial configuration.

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