scholarly journals Hinode observations of flares and active region emergence

2013 ◽  
Vol 440 ◽  
pp. 012002 ◽  
Author(s):  
Toshifumi Shimizu
Keyword(s):  
Active Region ◽  
Region Emergence

scholarly journals Magnetic Helicity Propagation from Inside the Sun

2005 ◽  
Vol 13 ◽  
pp. 97-100
Author(s):  
Dana Longcope
Keyword(s):  
Active Region ◽  
Flux Tube ◽  
Convection Zone ◽  
Active Regions ◽  
Magnetic Helicity ◽  
The Sun ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Region Emergence

AbstractModels of twisted flux tube evolution provide a picture of how magnetic helicity is propagated through the solar convection zone into the corona. According to the models, helicity tends toward an approximately uniform length-density along a tube, rather than concentrating at wider portions. Coronal fields lengthen rapidly during active region emergence, requiring additional helicity to propagate from the submerged flux tube. Recent observations of emerging active regions show an evolution consistent with this prediction, and no evidence of helicity concentrating in wider sections.

scholarly journals Solar active region emergence and flare productivity

2006 ◽  
Vol 2 (14) ◽  
pp. 614-614
Author(s):  
Silvia C. Dalla ◽  
Lyndsay Fletcher ◽  
Nicholas A. Walton
Keyword(s):  
Active Region ◽  
Solar Active Region ◽  
Virtual Observatory ◽  
The Sun ◽  
A Value ◽  
Significant Difference ◽  
Region Emergence ◽  
Two Populations ◽  
East West ◽  
Flare Productivity

AbstractWe use the workflow capabilities of the AstroGrid Virtual Observatory system (<http://www.astrogrid.org>) to analyse the relation between flare productivity and location of Active Region (AR) emergence on the Sun. Specifically, we investigate whether emergence of a new region near existing ones results in increased productivity of the new and/or pre-existing AR. To address this question, we build a series of workflows that perform queries to catalogues of regions and flares, and operations on the results of the queries. There is a strong East-West asymmetry in the location of emergence of new regions. We do not find a significant difference between the flaring rate of paired and isolated regions, when we choose a value of 12° as the cutoff between the two populations.

scholarly journals Average surface flows before the formation of solar active regions and their relationship to the supergranulation pattern

2019 ◽  
Vol 628 ◽  
pp. A37 ◽  
Author(s):  
A. C. Birch ◽  
H. Schunker ◽  
D. C. Braun ◽  
L. Gizon
Keyword(s):  
Simple Model ◽  
Active Region ◽  
Active Regions ◽  
Convergence Region ◽  
Near Surface ◽  
Surface Flows ◽  
Quiet Sun ◽  
Horizontal Flows ◽  
Solar Active Regions ◽  
Region Emergence

Context. The emergence of solar active regions is an important but poorly understood aspect of the solar dynamo. Aims. Knowledge of the flows associated with the rise of active-region-forming magnetic concentrations through the near-surface layers will help determine the mechanisms of active region formation. Methods. We used helioseismic holography and granulation tracking to measure the horizontal flows at the surface that precede the emergence of active regions. We then averaged these flows over about sixty emerging active regions to reduce the noise, selecting active regions that emerge into relatively quiet Sun. To help interpret the results, we constructed a simple model flow field by generating synthetic “emergence locations” that are probabilistically related to the locations of supergranulation-scale convergence regions in the quiet Sun. Results. The flow maps obtained from helioseismology and granulation tracking are very similar (correlation coefficients for single maps around 0.96). We find that active region emergence is, on average, preceded by converging horizontal flows of amplitude about 40 m s−1. The convergence region extends over about 40 Mm in the east-west direction and about 20 Mm in the north-south direction and is centered in the retrograde direction relative to the emergence location. This flow pattern is largely reproduced by a model in which active region emergence occurs preferentially in the prograde direction relative to supergranulation inflows. Conclusions. Averaging over many active regions reveals a statistically significant pattern of near-surface flows prior to emergence. The qualitative success of our simple model suggests that rising flux concentrations and supergranule-scale flows interact during the emergence process.

scholarly journals Active Region Emergence and Remote Flares

Solar Physics ◽  
2016 ◽  
Vol 291 (2) ◽  
pp. 383-410 ◽  
Author(s):  
Yixing Fu ◽  
Brian T. Welsch
Keyword(s):  
Active Region ◽  
Region Emergence

Morphology of the flare-productive active region NOAA 9087

2020 ◽  
Vol 36 (3) ◽  
pp. 69-90
Author(s):  
S. N. Chornogor ◽  
◽  
N. N. Kondrashova ◽  
Keyword(s):  
Active Region ◽  
Active Region Noaa ◽  
Region Noaa

On-the-Fly Determination of Active Region Centers in Adaptive-Partitioning QM/MM

2020 ◽  
Author(s):  
Zenghui Yang
Keyword(s):  
Quantum Mechanics ◽  
Active Region ◽  
Molecular Mechanics ◽  
Active Regions ◽  
Available Energy ◽  
Adaptive Partitioning ◽  
Different Levels

Quantum mechanics/molecular mechanics (QM/MM) methods partition the system into active and environmental regions and treat them with different levels of theory, achieving accuracy and efficiency at the same time. Adaptive-partitioning (AP) QM/MM methods allow on-the-fly changes to the QM/MM partitioning of the system. Many of the available energy-based AP-QM/MM methods partition the system according to distances to pre-chosen centers of active regions. For such AP-QM/MM methods, I develop an adaptive-center (AC) method that allows on-the-fly determination of the centers of active regions according to general geometrical or potential-related criteria, extending the range of application of energy-based AP-QM/MM methods to systems where active regions may occur or vanish during the simulation.

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