Wing-wing Interaction - When Exoplanets interact with each other 

2021 ◽  
Author(s):  
Christian Fischer ◽  
Joachim Saur
Keyword(s):  
Field Line ◽  
Open Field ◽  
Temporal Evolution ◽  
Three Dimensional ◽  
Time Variability ◽  
Poynting Flux ◽  
Open Field Line ◽  
Magnetohydrodynamic Model ◽  
Field Lines ◽  
Wing Interaction

<p>Electromagnetic Star-Planet Interaction is a phenomenon that occurs when a planet is sufficiently close to its host star that Alfvén waves propagate to the star and can leave an imprint on the star. The resulting structure is called Alfvén wing. Stars also often have open field-line structures due to the influence of the stellar wind. In these open field line regions, two planets can share the same set of field lines at the same time. Therefore, it is possible that Alfvén wings interact with each other and cause a time-variability in the signal. We call this process wing-wing interaction. To understand wing-wing interaction further, we apply a three dimensional, fully time-dependent, magnetohydrodynamic model. There, we simulate two planets that generate star-planet interaction and eventually undergo wing-wing interaction. We present the temporal evolution of the Alfvén wings and of the Poynting flux. From these results, we can estimate how wing-wing interaction could appear in observations. </p>

scholarly journals Large polar caps for twisted magnetosphere of magnetars

2019 ◽  
Author(s):  
H Tong
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Energy Release ◽  
Open Field ◽  
Magnetic Energy ◽  
Hot Spot ◽  
Open Field Line ◽  
Field Lines ◽  
The Magnetic Field ◽  
Magnetic Energy Release

Abstract The magnetic field of magnetars may be twisted compared with that of normal pulsars. Previous works mainly discussed magnetic energy release in the closed field line regions of magnetars. For a twisted magnetic field, the field lines will inflate in the radial direction. Similar to normal pulsars, the idea of light cylinder radius is introduced. More field lines will cross the light cylinder and become open for a twisted magnetic field. Therefore, magnetars may have a large polar cap, which may correspond to the hot spot during outburst. Particle flow in the open field line regions will result in the untwisting of the magnetic field. Magnetic energy release in the open field line regions can be calculated. The model calculations can catch the general trend of magnetar outburst: decreasing X-ray luminosity, shrinking hot spot etc. For magnetic energy release in the open field line regions, the geometry will be the same for different outburst in one magnetar.

scholarly journals Gyrokinetic continuum simulation of turbulence in a straight open-field-line plasma

2017 ◽  
Vol 83 (3) ◽  
Author(s):  
E. L. Shi ◽  
G. W. Hammett ◽  
T. Stoltzfus-Dueck ◽  
A. Hakim
Keyword(s):  
Magnetic Field ◽  
Boundary Conditions ◽  
Field Line ◽  
Open Field ◽  
Turbulent Transport ◽  
Numerical Approach ◽  
Long Wavelength ◽  
Plasma Device ◽  
Open Field Line ◽  
Field Lines

Five-dimensional gyrokinetic continuum simulations of electrostatic plasma turbulence in a straight, open-field-line geometry have been performed using a full-$f$discontinuous-Galerkin approach implemented in the Gkeyll code. While various simplifications have been used for now, such as long-wavelength approximations in the gyrokinetic Poisson equation and the Hamiltonian, these simulations include the basic elements of a fusion-device scrape-off layer: localised sources to model plasma outflow from the core, cross-field turbulent transport, parallel flow along magnetic field lines, and parallel losses at the limiter or divertor with sheath-model boundary conditions. The set of sheath-model boundary conditions used in the model allows currents to flow through the walls. In addition to details of the numerical approach, results from numerical simulations of turbulence in the Large Plasma Device, a linear device featuring straight magnetic field lines, are presented.

scholarly journals Differential rotation in neutron stars with open and closed magnetic topologies

2020 ◽  
Vol 494 (3) ◽  
pp. 3095-3109
Author(s):  
F Anzuini ◽  
A Melatos
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Open Field ◽  
Flux Tube ◽  
Differential Rotation ◽  
Time Scale ◽  
Outer Sphere ◽  
Closed Field ◽  
Magnetic Tension ◽  
Field Lines

ABSTRACT Analytic arguments have been advanced that the degree of differential rotation in a neutron star depends on whether the topology of the internal magnetic field is open or closed. To test this assertion, the ideal-magnetohydrodynamics solver pluto is employed to investigate numerically the flow of an incompressible, viscous fluid threaded by a magnetic field with open and closed topologies in a conducting, differentially rotating, spherical shell. Rigid body corotation with the outer sphere is enforced on the Alfvén time-scale, along magnetic field lines that connect the northern and southern hemispheres of the outer sphere. Along other field lines, however, the behaviour is more complicated. For example, an initial point dipole field evolves to produce an approximately closed equatorial flux tube containing at least one predominantly toroidal and approximately closed field line surrounded by a bundle of predominantly toroidal but open field lines. Inside the equatorial flux tube, the field-line-averaged magnetic tension approaches zero, and the fluid rotates differentially, adjusting its angular velocity on the viscous time-scale to match the boundary conditions on the flux tube’s toroidal surface. Outside the equatorial flux tube, the differential rotation increases, as the magnetic tension averaged along open field lines decreases.

Role and Contribution of the Open Field Line Region in the Large Helical Device

2007 ◽  
Vol 51 (2T) ◽  
pp. 147-149
Author(s):  
T. Watanabe ◽  
S. Masuzaki ◽  
Y. Nakamura ◽  
H. Hojo ◽  
Keyword(s):  
Field Line ◽  
Open Field ◽  
Line Region ◽  
Open Field Line

scholarly journals Equatorial spread <I>F</I> fossil plumes

2010 ◽  
Vol 28 (11) ◽  
pp. 2059-2069 ◽  
Author(s):  
J. Krall ◽  
J. D. Huba ◽  
S. L. Ossakow ◽  
G. Joyce
Keyword(s):  
High Altitude ◽  
Field Line ◽  
Mass Density ◽  
Three Dimensional ◽  
Simulation Code ◽  
Airglow Image ◽  
Spread F ◽  
Field Lines ◽  
Dimensional Simulation ◽  
Constant Altitude

Abstract. Behaviour of equatorial spread F (ESF) fossil plumes, i.e., ESF plumes that have stopped rising, is examined using the NRL SAMI3/ESF three-dimensional simulation code. We find that fossil bubbles, plasma density depletions associated with fossil plumes, can persist as high-altitude equatorial depletions even while being "blown" by zonal winds. Corresponding airglow-proxy images of fossil plumes, plots of electron density versus longitude and latitude at a constant altitude of 288 km, are shown to partially "fill in" in most cases, beginning with the highest altitude field lines within the plume. Specifically, field lines upon which the E field has fallen entirely to zero are affected and only the low altitude (≤600 km) portion if each field line fills in. This suggests that it should be possible to observe a bubble at high altitude on a field line for which the corresponding airglow image no longer shows a depletion. In all cases ESF plumes stop rising when the flux-tube-integrated ion mass density inside the upper edge of the bubble is equal to that of the nearby background, further supporting the result of Krall et al. (2010b).

scholarly journals MHD turbulence and heating of the open field-line solar corona

2003 ◽  
Vol 10 (1/2) ◽  
pp. 93-100 ◽  
Author(s):  
W. H. Matthaeus ◽  
D. J. Mullan ◽  
P. Dmitruk ◽  
L. Milano ◽  
S. Oughton
Keyword(s):  
Solar Corona ◽  
Field Line ◽  
Open Field ◽  
Coronal Holes ◽  
Low Frequency ◽  
Small Scale ◽  
Mhd Turbulence ◽  
Ion Heating ◽  
Open Field Line ◽  
Intense Electron Beams

Abstract. This paper discusses the possibility that heating of the solar corona in open field-line regions emanating from coronal holes is due to a nonlinear cascade, driven by low-frequency or quasi-static magnetohydrodynamic fluctuations. Reflection from coronal inhomogeneities plays an important role in sustaining the cascade. Physical and observational constraints are discussed. Kinetic processes that convert cascaded energy into heat must occur in regions of turbulent small-scale reconnection, and may be similar in some respects to ion heating due to intense electron beams observed in the aurora.

Parallel heat flux and flow acceleration in open field line plasmas with magnetic trapping

2014 ◽  
Vol 21 (10) ◽  
pp. 102512 ◽  
Author(s):  
Zehua Guo ◽  
Xian-Zhu Tang ◽  
Chris McDevitt
Keyword(s):  
Heat Flux ◽  
Field Line ◽  
Open Field ◽  
Magnetic Trapping ◽  
Flow Acceleration ◽  
Open Field Line
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