scholarly journals An MHD simulation model of time-dependent global solar corona with temporally varying solar-surface magnetic field maps

2013 ◽  
Vol 118 (11) ◽  
pp. 6889-6906 ◽  
Author(s):  
K. Hayashi
Keyword(s):  
Magnetic Field ◽  
Simulation Model ◽  
Solar Corona ◽  
Solar Surface ◽  
Time Dependent ◽  
Mhd Simulation ◽  
Surface Magnetic Field

scholarly journals Investigating Magnetic Activity in the Galactic Centre by Global MHD Simulation

2016 ◽  
Vol 11 (S322) ◽  
pp. 137-140
Author(s):  
Takeru K. Suzuki ◽  
Yasuo Fukui ◽  
Kazufumi Torii ◽  
Mami Machida ◽  
Ryoji Matsumoto ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Gas Flow ◽  
Rotation Frequency ◽  
Magnetic Activity ◽  
Time Dependent ◽  
Galactic Centre ◽  
Dependent Manner ◽  
Mhd Simulation ◽  
Magnetic Buoyancy ◽  
Bulge Region

AbstractBy performing a global magnetohydrodynamical (MHD) simulation for the Milky Way with an axisymmetric gravitational potential, we propose that spatially dependent amplification of magnetic fields possibly explains the observed noncircular motion of the gas in the Galactic centre (GC) region. The radial distribution of the rotation frequency in the bulge region is not monotonic in general. The amplification of the magnetic field is enhanced in regions with stronger differential rotation, because magnetorotational instability and field-line stretching are more effective. The strength of the amplified magnetic field reaches ≳ 0.5 mG, and radial flows of the gas are excited by the inhomogeneous transport of angular momentum through turbulent magnetic field that is amplified in a spatially dependent manner. As a result, the simulated position-velocity diagram exhibits a time-dependent asymmetric parallelogram-shape owing to the intermittency of the magnetic turbulence; the present model provides a viable alternative to the bar-potential-driven model for the parallelogram shape of the central molecular zone. In addition, Parker instability (magnetic buoyancy) creates vertical magnetic structure, which would correspond to observed molecular loops, and frequently excited vertical flows. Furthermore, the time-averaged net gas flow is directed outward, whereas the flows are highly time dependent, which would contribute to the outflow from the bulge.

scholarly journals Holes in the Solar Corona

1975 ◽  
Vol 68 ◽  
pp. 19-21
Author(s):  
W. M. Glencross
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Solar Corona ◽  
Field Component ◽  
Solar Surface ◽  
Field Direction ◽  
The Other ◽  
Flux Tubes ◽  
Sequence Of Events

SummaryBabcock (1961) outlined the sequence of events which takes place in the Sun's atmosphere during a solar cycle. Magnetic field loops, having preferred directions, emerge from the solar surface and thereafter merge with neighbouring loops to produce more extended structures. Although flux tubes emerge with a strong E-W field component, having the field direction reversed from one side of the equator to the other, there is a tendency for the longer loops produced by merging to have a significant N-S alignment (Hansen et al., 1972).

scholarly journals MESOGRANULATION AND THE SOLAR SURFACE MAGNETIC FIELD DISTRIBUTION

2011 ◽  
Vol 727 (2) ◽  
pp. L30 ◽  
Author(s):  
L. Yelles Chaouche ◽  
F. Moreno-Insertis ◽  
V. Martínez Pillet ◽  
T. Wiegelmann ◽  
J. A. Bonet ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Distribution ◽  
Solar Surface ◽  
Magnetic Field Distribution ◽  
Surface Magnetic Field

scholarly journals Photospheric downflows observed with SDO/HMI, HINODE, and an MHD simulation

2021 ◽  
Vol 647 ◽  
pp. A178
Author(s):  
T. Roudier ◽  
M. Švanda ◽  
J. M. Malherbe ◽  
J. Ballot ◽  
D. Korda ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Surface ◽  
Outer Part ◽  
Data Cube ◽  
The Sun ◽  
Solar Dynamics Observatory ◽  
Mhd Simulation ◽  
Quiet Sun ◽  
Solar Dynamics ◽  
The Magnetic Field

Downflows on the solar surface are suspected to play a major role in the dynamics of the convection zone, at least in its outer part. We investigate the existence of the long-lasting downflows whose effects influence the interior of the Sun but also the outer layers. We study the sets of Dopplergrams and magnetograms observed with Solar Dynamics Observatory and Hinode spacecrafts and an magnetohydrodynamic (MHD) simulation. All of the aligned sequences, which were corrected from the satellite motions and tracked with the differential rotation, were used to detect the long-lasting downflows in the quiet-Sun at the disc centre. To learn about the structure of the flows below the solar surface, the time-distance local helioseismology was used. The inspection of the 3D data cube (x, y, t) of the 24 h Doppler sequence allowed us to detect 13 persistent downflows. Their lifetimes lie in the range between 3.5 and 20 h with a sizes between 2″ and 3″ and speeds between −0.25 and −0.72 km s−1. These persistent downflows are always filled with the magnetic field with an amplitude of up to 600 Gauss. The helioseismic inversion allows us to describe the persistent downflows and compare them to the other (non-persistent) downflows in the field of view. The persistent downflows seem to penetrate much deeper and, in the case of a well-formed vortex, the vorticity keeps its integrity to the depth of about 5 Mm. In the MHD simulation, only sub-arcsecond downflows are detected with no evidence of a vortex comparable in size to observations at the surface of the Sun. The long temporal sequences from the space-borne allows us to show the existence of long-persistent downflows together with the magnetic field. They penetrate inside the Sun but are also connected with the anchoring of coronal loops in the photosphere, indicating a link between downflows and the coronal activity. A links suggests that EUV cyclones over the quiet Sun could be an effective way to heat the corona.

scholarly journals Preliminary design of the INPE's Solar Vector Magnetograph

2014 ◽  
Vol 10 (S305) ◽  
pp. 195-199 ◽  
Author(s):  
L. E. A. Vieira ◽  
A. L. Clúa de Gonzalez ◽  
A. Dal Lago ◽  
C. Wrasse ◽  
E. Echer ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Visible Light ◽  
Solar Surface ◽  
Solar Physics ◽  
Solar Photosphere ◽  
Preliminary Design ◽  
Nearby Star ◽  
Surface Magnetic Field ◽  
Starting Point ◽  
The Magnetic Field

AbstractWe describe the preliminary design of a magnetograph and visible-light imager instrument to study the solar dynamo processes through observations of the solar surface magnetic field distribution. The instrument will provide measurements of the vector magnetic field and of the line-of-sight velocity in the solar photosphere. As the magnetic field anchored at the solar surface produces most of the structures and energetic events in the upper solar atmosphere and significantly influences the heliosphere, the development of this instrument plays an important role in reaching the scientific goals of The Atmospheric and Space Science Coordination (CEA) at the Brazilian National Institute for Space Research (INPE). In particular, the CEA's space weather program will benefit most from the development of this technology. We expect that this project will be the starting point to establish a strong research program on Solar Physics in Brazil. Our main aim is acquiring progressively the know-how to build state-of-the-art solar vector magnetograph and visible-light imagers for space-based platforms to contribute to the efforts of the solar-terrestrial physics community to address the main unanswered questions on how our nearby Star works.

scholarly journals Investigation of Coronal Properties of X-Ray Bright G-dwarf Stars Based on the Solar Surface Magnetic Field–Corona Relationship

2020 ◽  
Vol 901 (1) ◽  
pp. 70
Author(s):  
Shinsuke Takasao ◽  
Ikuyuki Mitsuishi ◽  
Takuma Shimura ◽  
Atsushi Yoshida ◽  
Masanobu Kunitomo ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Surface ◽  
Dwarf Stars ◽  
X Ray ◽  
Surface Magnetic Field

High Speed Solar Wind Forecast Model from the Solar Surface to 1AU Using Global 3D MHD Simulation

2017 ◽  
Vol 13 (S335) ◽  
pp. 272-275
Author(s):  
Mitsue Den ◽  
Takashi Tanaka ◽  
Yuki Kubo ◽  
Shinichi Watari
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
High Speed ◽  
Weather Forecasting ◽  
Solar Surface ◽  
Wind Condition ◽  
Geomagnetic Disturbances ◽  
Mhd Simulation ◽  
Speed Solar Wind ◽  
High Speed Solar Wind

AbstractEmanating from coronals holes (CHs), high speed streams (HSSs) cause recurrent geomagnetic disturbances in the Earth’s magnetosphere. For this reason being able to predict the occurrence and timing of the high speed solar wind is one of the more important issues in space weather forecasting. Currently, it is still difficult to estimate the effect of a CH in case that it extends from high latitudes to lower ones. To monitor the global solar wind condition we have therefore developed a three-dimensional MHD simulation code, the REProduce Plasma Universe (REPPU) code, that is driven by the solar magnetic field from the solar surface to 1AU. The connectivity of magnetic field lines from CHs to Earth’s orbit via HSSs has been investigated. Simulation results are presented and the usefulness of our model is discussed.

scholarly journals Time-dependent MHD modeling of the global solar corona for year 2007: Driven by daily-updated magnetic field synoptic data

2012 ◽  
Vol 117 (A8) ◽  
pp. n/a-n/a ◽  
Author(s):  
L. P. Yang ◽  
X. S. Feng ◽  
C. Q. Xiang ◽  
Yang Liu ◽  
Xuepu Zhao ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Time Dependent ◽  
Mhd Modeling

scholarly journals Magnetopause reconnection and interlinked flux tubes

2013 ◽  
Vol 31 (10) ◽  
pp. 1853-1866 ◽  
Author(s):  
F. R. Cardoso ◽  
W. D. Gonzalez ◽  
D. G. Sibeck ◽  
M. Kuznetsova ◽  
D. Koga
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Magnetic Reconnection ◽  
Large Scale ◽  
Time Dependent ◽  
Mhd Simulation ◽  
Flux Tubes ◽  
Magnetic Structures ◽  
Mhd Simulations ◽  
Magnetopause Reconnection

Abstract. Magnetic reconnection can be a continuous or a transient process. Global magnetohydrodynamics (MHD) simulations are important tools to understand the relevant magnetic reconnection mechanisms and the resulting magnetic structures. We have studied magnetopause reconnection using a global 3-D MHD simulation in which the interplanetary magnetic field (IMF) has been set to large positive By and large negative Bz components, i.e., a south-duskward direction. Flux tubes have been observed even during these constant solar wind conditions. We have focused on the interlinked flux tubes event resulting from time-dependent, patchy and multiple reconnection. At the event onset, two reconnection modes seem to occur simultaneously: a time-dependent, patchy and multiple reconnection for the subsolar region; and, a steady and large-scale reconnection for the regions far from the subsolar site.

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