scholarly journals Comparative case study of two methods to assess the eruptive potential of selected active regions

2022 ◽  
Vol 21 (12) ◽  
pp. 313
Author(s):  
Francesca Zuccarello ◽  
Ilaria Ermolli ◽  
Marianna B. Korsós ◽  
Fabrizio Giorgi ◽  
Salvo L. Guglielmino ◽  
...  
Keyword(s):  
Active Regions ◽  
Weather Conditions ◽  
Comparative Case Study ◽  
Physical Parameters ◽  
Electromagnetic Spectrum ◽  
Solar Dynamics Observatory ◽  
Terrestrial Environment ◽  
Near Earth Space ◽  
Solar Dynamics

Abstract Solar eruptive events, like flares and coronal mass ejections, are characterized by the rapid release of energy that can give rise to emission of radiation across the entire electromagnetic spectrum and to an abrupt significant increase in the kinetic energy of particles. These energetic phenomena can have important effects on the space weather conditions and therefore it is necessary to understand their origin, in particular, what is the eruptive potential of an active region (AR). In these case studies, we compare two distinct methods that were used in previous works to investigate the variations of some characteristic physical parameters during the pre-flare states of flaring ARs. These methods consider: i) the magnetic flux evolution and magnetic helicity accumulation, and ii) the fractal and multi-fractal properties of flux concentrations in ARs. Our comparative analysisis based on time series of photospheric data obtained bythe Solar Dynamics Observatory between March 2011 and June 2013. We selected two distinct samples of ARs: one is distinguished by the occurrence of more energetic M- and X-class flare events, that may have a rapid effect on not just the near-Earth space, but also on the terrestrial environment; the second is characterized by no-flares or having just a few C- and B-class flares. We foundthat the two tested methods complement each other in their ability to assess the eruptive potentials of ARs and could be employed to identify ARs prone to flaring activity. Based on the presented case study, we suggest that using a combination of different methods may aid to identify more reliably the eruptive potentials of ARs and help to better understand the pre-flare states.

scholarly journals Observation and simulation of a filament eruption associated with the contraction of the overlying coronal loops and the filament rotation

2013 ◽  
Vol 8 (S300) ◽  
pp. 504-506
Author(s):  
X. L. Yan ◽  
Z. K. Xue ◽  
Z. X. Mei
Keyword(s):  
Coronal Loop ◽  
Coronal Loops ◽  
Solar Dynamics Observatory ◽  
Filament Eruption ◽  
Solar Dynamics ◽  
Rotation Motion

AbstractBy using the data of Solar Dynamics Observatory (SDO), we present a case study of the contraction of the overlying coronal loop and the rotation motion of a sigmoid filament on 2012 May 22. At the beginning of the filament eruption, the overlying coronal loop experienced a significant contraction. In the following, the filament started to rotate counterclockwise. We also carried the simulation to investigate the process of the filament eruption.

scholarly journals Nature of the energy source powering solar coronal loops driven by nanoflares

2018 ◽  
Vol 615 ◽  
pp. L9 ◽  
Author(s):  
L. P. Chitta ◽  
H. Peter ◽  
S. K. Solanki
Keyword(s):  
Magnetic Field ◽  
Energy Source ◽  
Extreme Ultraviolet ◽  
Magnetic Energy ◽  
Plasma Heating ◽  
Active Regions ◽  
Coronal Loops ◽  
Solar Dynamics Observatory ◽  
Mixed Polarity ◽  
Solar Dynamics

Context. Magnetic energy is required to heat the corona, the outer atmosphere of the Sun, to millions of degrees. Aims. We study the nature of the magnetic energy source that is probably responsible for the brightening of coronal loops driven by nanoflares in the cores of solar active regions. Methods. We consider observations of two active regions (ARs), 11890 and 12234, in which nanoflares have been detected. To this end, we use ultraviolet (UV) and extreme ultraviolet (EUV) images from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) for coronal loop diagnostics. These images are combined with the co-temporal line-of-sight magnetic field maps from the Helioseismic and Magnetic Imager (HMI) onboard SDO to investigate the connection between coronal loops and their magnetic roots in the photosphere. Results. The core of these ARs exhibit loop brightening in multiple EUV channels of AIA, particularly in its 9.4 nm filter. The HMI magnetic field maps reveal the presence of a complex mixed polarity magnetic field distribution at the base of these loops. We detect the cancellation of photospheric magnetic flux at these locations at a rate of about 1015 Mx s−1. The associated compact coronal brightenings directly above the cancelling magnetic features are indicative of plasma heating due to chromospheric magnetic reconnection. Conclusions. We suggest that the complex magnetic topology and the evolution of magnetic field, such as flux cancellation in the photosphere and the resulting chromospheric reconnection, can play an important role in energizing active region coronal loops driven by nanoflares. Our estimate of magnetic energy release during flux cancellation in the quiet Sun suggests that chromospheric reconnection can also power the quiet corona.

scholarly journals EMERGING DIMMINGS OF ACTIVE REGIONS OBSERVED BY THE SOLAR DYNAMICS OBSERVATORY

2012 ◽  
Vol 760 (2) ◽  
pp. L29 ◽  
Author(s):  
Jun Zhang ◽  
Shuhong Yang ◽  
Yang Liu ◽  
Xudong Sun
Keyword(s):  
Active Regions ◽  
Solar Dynamics Observatory ◽  
Solar Dynamics

scholarly journals Impulsive coronal heating during the interaction of surface magnetic fields in the lower solar atmosphere

2020 ◽  
Vol 644 ◽  
pp. A130
Author(s):  
L. P. Chitta ◽  
H. Peter ◽  
E. R. Priest ◽  
S. K. Solanki
Keyword(s):  
Solar Surface ◽  
Magnetic Energy ◽  
Active Regions ◽  
Opposite Polarity ◽  
Space Mission ◽  
Magnetic Polarity ◽  
Coronal Heating ◽  
Coronal Loops ◽  
Solar Dynamics Observatory ◽  
Solar Dynamics

Coronal plasma in the cores of solar active regions is impulsively heated to more than 5 MK. The nature and location of the magnetic energy source responsible for such impulsive heating is poorly understood. Using observations of seven active regions from the Solar Dynamics Observatory, we found that a majority of coronal loops hosting hot plasma have at least one footpoint rooted in regions of interacting mixed magnetic polarity at the solar surface. In cases when co-temporal observations from the Interface Region Imaging Spectrograph space mission are available, we found spectroscopic evidence for magnetic reconnection at the base of the hot coronal loops. Our analysis suggests that interactions of magnetic patches of opposite polarity at the solar surface and the associated energy release during reconnection are key to impulsive coronal heating.

scholarly journals Recurrent filament eruptions and associated CMEs

2013 ◽  
Vol 8 (S300) ◽  
pp. 489-490
Author(s):  
Brigitte Schmieder ◽  
Hebe Cremades ◽  
Cristina Mandrini ◽  
Pascal Démoulin ◽  
Yang Guo
Keyword(s):  
Magnetic Field ◽  
Field Intensity ◽  
Magnetic Field Intensity ◽  
Active Regions ◽  
The Other ◽  
Magnetic Configuration ◽  
Solar Dynamics Observatory ◽  
Solar Dynamics ◽  
Topology Computation ◽  
The Magnetic Field

AbstractWe investigate the violent events in the cluster of two active regions (ARs), NOAA numbers 11121 and 11123, observed on 11 November 2010 by the Solar Dynamics Observatory (SDO). Within one day the magnetic field intensity increased by 70% with the emergence of new groups of bipoles in AR 11123, where three filaments are seen along the complex inversion line. The destabilization of the filaments led to flares and CMEs. The CMEs around 08:24 UT and 17:00 UT are directly related to the partial eruption of one filament in the new AR, as shown by a topology computation and analysis. The other CMEs on this day are due to either other ARs or to the destabilization of the global magnetic configuration of the two ARs. This conclusion can be only reached by using the three eyes of SOHO, STEREO and SDO.

scholarly journals Automating Ellerman bomb detection in ultraviolet continua

2019 ◽  
Vol 626 ◽  
pp. A4 ◽  
Author(s):  
Gregal J. M. Vissers ◽  
Luc H. M. Rouppe van der Voort ◽  
Robert J. Rutten
Keyword(s):  
Imaging Spectroscopy ◽  
Active Regions ◽  
Optimal Recovery ◽  
Data Sets ◽  
Solar Dynamics Observatory ◽  
Flux Dynamics ◽  
Disc Centre ◽  
Solar Dynamics ◽  
Selection Of ◽  
Ellerman Bombs

Ellerman bombs are transient brightenings in the wings of Hα 6563 Å that pinpoint photospheric sites of magnetic reconnection in solar active regions. Their partial visibility in the 1600 Å and 1700 Å continua registered routinely by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) offers a unique opportunity to inventory such magnetic-field disruptions throughout the AIA database if a reliable recipe for their detection can be formulated. This is done here. We have improved and applied an Hα Ellerman bomb detection code to ten data sets spanning viewing angles from solar disc centre to the limb. They combine high-quality Hα imaging spectroscopy from the Swedish 1 m Solar Telescope with simultaneous AIA imaging around 1600 Å and 1700 Å. A trial grid of brightness, lifetime and area constraints is imposed on the AIA images to define optimal recovery of the 1735 Ellerman bombs detected in Hα. The best results when optimising simultaneously for recovery fraction and reliability are obtained from 1700 Å images by requiring 5σ brightening above the average 1700 Å nearby quiet-Sun intensity, lifetime above one minute, area of 1–18 AIA pixels. With this recipe 27% of the AIA detections are Hα-detected Ellerman bombs while it recovers 19% of these (of which many are smaller than the AIA resolution). Better yet, among the top 10% AIA 1700 Å detections selected with combined brightness, lifetime and area thresholds as many as 80% are Hα Ellerman bombs. Automated selection of the best 1700 Å candidates therefore opens the entire AIA database for detecting most of the more significant photospheric reconnection events. This proxy is applicable as a flux-dynamics tell-tale in studying any Earth-side solar active region since early 2010 up to the present.

scholarly journals The rotation rate of solar active and ephemeral regions – I. Dependence on morphology and peak magnetic flux

2020 ◽  
Vol 500 (4) ◽  
pp. 5159-5166
Author(s):  
Alexander S Kutsenko
Keyword(s):  
Rotation Rate ◽  
Convection Zone ◽  
Active Regions ◽  
Solar Dynamics Observatory ◽  
Convective Envelope ◽  
Near Surface ◽  
Rotation Rates ◽  
Significant Difference ◽  
Class B ◽  
Solar Dynamics

ABSTRACT Using magnetic field maps acquired by the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory, we measured rotation rates of 864 active and 322 ephemeral regions observed between 2010 and 2016. We found smaller magnetic tracers to show a tendency to rotate faster as compared to larger ones. Thus, ephemeral regions exhibit on average the fastest rotation rate. We further divided active regions into three classes. Class A comprised magnetic bipoles obeying Hale’s polarity law, Joy’s law, and exhibiting more coherent leading polarity in comparison with the following one. The second class B included active regions violating at least one of the aforementioned empirical laws. The third class U comprised unipolar active regions. We found no significant difference between the rotation rates of active regions of classes A and B. In contrast, unipolar active regions exhibited on average lower rotation rate and narrower distribution of the rotation rate differences. Assuming the rotation rate to indicate the anchoring depth of the magnetic structure within the convection zone, we supposed that active regions of classes A and B might be anchored throughout the entire convective envelope while unipolar active regions a rooted within a thin layer located either near the base of the convection zone or at a shallow near-surface depth.

CORONAL HEATING BY THE INTERACTION BETWEEN EMERGING ACTIVE REGIONS AND THE QUIET SUN OBSERVED BY THE SOLAR DYNAMICS OBSERVATORY

2015 ◽  
Vol 799 (2) ◽  
pp. L27 ◽  
Author(s):  
Jun Zhang ◽  
Bin Zhang ◽  
Ting Li ◽  
Shuhong Yang ◽  
Yuzong Zhang ◽  
...  
Keyword(s):  
Active Regions ◽  
Coronal Heating ◽  
Solar Dynamics Observatory ◽  
Quiet Sun ◽  
Solar Dynamics
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