Canonical orbital contributions to the magnetic fields induced by global and local diatropic and paratropic ring currents

2017 ◽  
Vol 38 (30) ◽  
pp. 2594-2604 ◽  
Author(s):  
Nickolas D. Charistos ◽  
Anastasios G. Papadopoulos ◽  
Thomas A. Nikopoulos ◽  
Alvaro Muñoz-Castro ◽  
Michael P. Sigalas
Keyword(s):  
Magnetic Fields ◽  
Ring Currents ◽  
Global And Local

scholarly journals Coronal Holes in Global Complexes of Activity

2015 ◽  
Vol 2015 ◽  
pp. 1-9
Author(s):  
Vladimir N. Obridko ◽  
Bertha D. Shelting
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Coronal Holes ◽  
Active Regions ◽  
Local Fields ◽  
Magnetic Region ◽  
Single Process ◽  
Global And Local ◽  
The Relationship ◽  
The Magnetic Field

We propose a new concept that considers the global complexes of activity as a combination of global and local fields. Traditionally, the complexes of activity have been identified from observations of active regions (ARs). Here, we show that a complex of activity comprises both (AR) and coronal holes (CHs). Our analysis is based on observations of magnetic fields of various scales, SOHO/MDI data, and UV observations of CH. The analysis has corroborated the existence of complexes of activity that involve AR and equatorial CH. Both AR and CH are embedded in an extended magnetic region dominated by the magnetic field of one sign, but not strictly unipolar. It is shown that the evolution of CH and AR is a single process. The relationship between the fields of various scales in the course of a cycle is discussed.

scholarly journals Is magnetic topology important for heating the solar atmosphere?

2015 ◽  
Vol 373 (2042) ◽  
pp. 20140264 ◽  
Author(s):  
Clare E. Parnell ◽  
Julie E. H. Stevenson ◽  
James Threlfall ◽  
Sarah J. Edwards
Keyword(s):  
Magnetic Fields ◽  
Open Field ◽  
Solar Atmosphere ◽  
Active Regions ◽  
Energy Losses ◽  
Wave Dissipation ◽  
Quiet Sun ◽  
Topological Features ◽  
Complex Topology ◽  
Global And Local

Magnetic fields permeate the entire solar atmosphere weaving an extremely complex pattern on both local and global scales. In order to understand the nature of this tangled web of magnetic fields, its magnetic skeleton, which forms the boundaries between topologically distinct flux domains, may be determined. The magnetic skeleton consists of null points, separatrix surfaces, spines and separators. The skeleton is often used to clearly visualize key elements of the magnetic configuration, but parts of the skeleton are also locations where currents and waves may collect and dissipate. In this review, the nature of the magnetic skeleton on both global and local scales, over solar cycle time scales, is explained. The behaviour of wave pulses in the vicinity of both nulls and separators is discussed and so too is the formation of current layers and reconnection at the same features. Each of these processes leads to heating of the solar atmosphere, but collectively do they provide enough heat, spread over a wide enough area, to explain the energy losses throughout the solar atmosphere? Here, we consider this question for the three different solar regions: active regions, open-field regions and the quiet Sun. We find that the heating of active regions and open-field regions is highly unlikely to be due to reconnection or wave dissipation at topological features, but it is possible that these may play a role in the heating of the quiet Sun. In active regions, the absence of a complex topology may play an important role in allowing large energies to build up and then, subsequently, be explosively released in the form of a solar flare. Additionally, knowledge of the intricate boundaries of open-field regions (which the magnetic skeleton provides) could be very important in determining the main acceleration mechanism(s) of the solar wind.

scholarly journals Generation of coupled global and local magnetic fields by a cellular MHD dynamo

2006 ◽  
Vol 2 (S239) ◽  
pp. 482-487
Author(s):  
A. V. Getling ◽  
R. D. Simitev ◽  
F. H. Busse
Keyword(s):  
Magnetic Fields ◽  
Stationary Regime ◽  
Polar Regions ◽  
Magnetic Structures ◽  
Local Structures ◽  
First Case ◽  
Mhd Dynamo ◽  
Electromagnetic Processes ◽  
Background Fields ◽  
Global And Local

AbstractThe convection-driven MHD dynamo in a rotating spherical shell is simulated numerically. Convection cells are regarded as a connecting link between the global and local electromagnetic processes. Local (in many cases, bipolar) magnetic structures are regularly produced by convection cells. Dynamo regimes in “thick” and “thin” shells are discussed. In the first case, the “general” magnetic field maintained by the dynamo has a sign-alternating dipolar component, which varies cyclically, although not periodically. The local structures, as they disintegrate, change into background fields, which drift toward the poles. From time to time, reversals of the magnetic fields in the polar regions occur, as “new” background fields expel the “old” fields. In the second case, the system settles down to a nearly stationary regime without polarity reversals.

scholarly journals Analysis of Local and Global Aromaticity in Si3C5 and Si4C8 Clusters. Aromatic Species Containing Planar Tetracoordinate Carbon

2021 ◽  
Author(s):  
Juan Torres-Vega ◽  
Diego R. Alcoba ◽  
Ofelia B. Oña ◽  
Alejandro Vasquez-Espinal ◽  
Rodrigo Báez-Grez ◽  
...  
Keyword(s):  
Current Density ◽  
Minimum Energy ◽  
Localization Method ◽  
Aromatic Character ◽  
Ring Currents ◽  
Local Current ◽  
Natural Density ◽  
Aromatic Species ◽  
Density Analysis ◽  
Global And Local

The minimum energy structures of the Si3C5 and Si4C8 clusters are planar and contain planar tetracoordinate carbons (ptCs). These species have been classified, qualitatively, as global () and local () aromatics according to the adaptive natural density partitioning (AdNDP) method, which is an orbital localization method. This work evaluates these species' aromaticity, focusing on confirming and quantifying their global and local aromatic character. For this purpose, we use an orbital localization method based on the partitioning of the molecular space according to the topology of the electronic localization function (LOC-ELF). In addition, the magnetically induced current density is analyzed. The LOC-ELF-based analysis coincides with the AdNDP study (double aromaticity, global and local). Besides, the current density analysis detects global and local ring currents. The strength of the global and local current circuit is significant, involving 4n+2 - and -electrons, respectively. The latter implicates the Si-ptC-Si fragment, which would be related to the 3c-2e -bond detected by the orbital localization methods in this fragment.

scholarly journals Analysis of Local and Global Aromaticity in Si3C5 and Si4C8 Clusters. Aromatic Species Containing Planar Tetracoordinate Carbon

Chemistry ◽  
2021 ◽  
Vol 3 (4) ◽  
pp. 1101-1112
Author(s):  
Juan J. Torres-Vega ◽  
Diego R. Alcoba ◽  
Ofelia B. Oña ◽  
Alejandro Vásquez-Espinal ◽  
Rodrigo Báez-Grez ◽  
...  
Keyword(s):  
Current Density ◽  
Minimum Energy ◽  
Localization Method ◽  
Aromatic Character ◽  
Ring Currents ◽  
Local Current ◽  
Natural Density ◽  
Aromatic Species ◽  
Density Analysis ◽  
Global And Local

The minimum energy structures of the Si3C5 and Si4C8 clusters are planar and contain planar tetracoordinate carbons (ptCs). These species have been classified, qualitatively, as global (π) and local (σ) aromatics according to the adaptive natural density partitioning (AdNDP) method, which is an orbital localization method. This work evaluates these species’ aromaticity, focusing on confirming and quantifying their global and local aromatic character. For this purpose, we use an orbital localization method based on the partitioning of the molecular space according to the topology of the electronic localization function (LOC-ELF). In addition, the magnetically induced current density is analyzed. The LOC-ELF-based analysis coincides with the AdNDP study (double aromaticity, global, and local). Moreover, the current density analysis detects global and local ring currents. The strength of the global and local current circuit is significant, involving 4n + 2 π- and σ-electrons, respectively. The latter implicates the Si-ptC-Si fragment, which would be related to the 3c-2e σ-bond detected by the orbital localization methods in this fragment.

On global and local magnetic fields of flare stars with YZ CMi and OT Ser as examples

2017 ◽  
Vol 72 (2) ◽  
pp. 178-183 ◽  
Author(s):  
V. D. Bychkov ◽  
L. V. Bychkova ◽  
J. Madej ◽  
A. A. Panferov
Keyword(s):  
Magnetic Fields ◽  
Flare Stars ◽  
Local Magnetic Fields ◽  
Global And Local
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