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The speed of sound greatly exceeds typical flow velocities in many stellar and planetary interiors. To follow the slow evolution of subsonic motions, various sound-proof models attempt to remove fast acoustic waves whilst retaining…

Solar and Stellar Astrophysics · Physics 2015-06-15 Geoffrey M. Vasil , Daniel Lecoanet , Benjamin P. Brown , Toby S. Wood , Ellen G. Zweibel

The standing quasi modes in a cylindrical incompressible flux tube with magnetic twist that undergoes a radial density structuring is considered in ideal magnetohydrodynamics (MHD). The radial structuring is assumed to be a linearly varying…

Solar and Stellar Astrophysics · Physics 2011-05-06 K. Karami , K. Bahari

With the ultimate aim of using the fundamental or $f$-mode to study helioseismic aspects of turbulence-generated magnetic flux concentrations, we use randomly forced hydromagnetic simulations of a piecewise isothermal layer in two…

Solar and Stellar Astrophysics · Physics 2015-06-19 Nishant K. Singh , Axel Brandenburg , S. M. Chitre , Matthias Rheinhardt

We gave an extensive study for the quasi-periodic perturbations on the time profiles of the line of sight (LOS) magnetic field in 10x10 sub-areas in a solar plage region (corresponds to a facula on the photosphere). The perturbations are…

Solar and Stellar Astrophysics · Physics 2022-04-20 Haisheng Ji , Parida Hashim , Zhenxiang Hong , Zhe Xu , Jinhua Shen , Kaifan Ji , Wenda Cao

Bearing in mind the application to the outer crust of the neutron stars (NSs), we investigate the magnetic field decay by means of the fully relativistic Particle-In-Cell simulations. Numerical computations are carried out in 2-dimensions,…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Hiroyuki R. Takahashi , Kei Kotake , Nobutoshi Yasutake

By numerically solving the equations of rotating magnetohydrodynamics (MHD), the magnetic effect on dynamical tide is studied. It is found that magnetic field has a significant impact not only on the flow structure, i.e. the internal shear…

Solar and Stellar Astrophysics · Physics 2018-02-21 Xing Wei

The main goal is to study the dynamics of the gravitationally stratified, field-free cavities in the solar atmosphere, located under small-scale, cylindrical magnetic canopies, in response to explosive events in the lower-lying regions (due…

Solar and Stellar Astrophysics · Physics 2013-02-28 D. Kuridze , T. V. Zaqarashvili , B. M. Shergelashvili , S. Poedts

Rapidly decaying slow magnetoacoustic waves are regularly observed in the solar coronal structures, offering a promising tool for a seismological diagnostics of the coronal plasma, including its thermodynamical properties. The effect of…

Solar and Stellar Astrophysics · Physics 2019-08-21 D. Y. Kolotkov , V. M. Nakariakov , D. I. Zavershinskii

We report results of the first global three-dimensional magnetohydrodynamic simulations of the waves excited in an accretion disc by a rotating star with a dipole magnetic field misaligned from the star's rotation axis (which is aligned…

Solar and Stellar Astrophysics · Physics 2013-03-20 M. M. Romanova , G. V. Ustyugova , A. V. Koldoba , R. V. E. Lovelace

We study local stability of the advection-dominated optically thick (slim) and optically thin discs with purely toroidal magnetic field and the radial viscous force using a linear perturbation analysis. Our dispersion relation indicates…

Astrophysics of Galaxies · Physics 2018-03-21 S. M. Ghoreyshi , Mohsen Shadmehri

We investigate the viability of MHD waves, in particular acoustic p-modes, in causing strong current accumulation at the null points. We begin with a three-dimensional numerical setup incorporating a gravitationally stratifed solar…

Solar and Stellar Astrophysics · Physics 2023-10-27 Nitin Yadav , Rony Keppens

We study the stability and the modes of non -- isothermal coronal loop models with different intensity values of the equilibrium twisted magnetic field.We use an energy principle obtained via non -- equilibrium thermodynamic arguments. The…

Astrophysics · Physics 2009-11-13 A. Costa , R. Gonzalez

Using the exact propagators in a constant magnetic field, the neutrino self-energy has been calculated to all orders in the field strength $B$ within the minimal extension of the Weinberg-Salam model with massive Dirac neutrinos. A neutrino…

High Energy Physics - Phenomenology · Physics 2020-11-03 Andrea Erdas , Zachary Metzler

The S=1/2, nearest-neighbor, kinetic Ising model has been used to model magnetization switching in nanoscale ferromagnets. For this model, earlier work based on the droplet theory of the decay of metastable phases and Monte Carlo…

Condensed Matter · Physics 2009-10-28 S. W. Sides , R. A. Ramos , P. A. Rikvold , M. A. Novotny

The presence of intense magnetic fields in and around sunspots is expected to modify the solar structure and oscillation frequencies. Applying the ring diagram technique to data from the Michelson Doppler Imager (MDI) on board the Solar and…

Astrophysics · Physics 2009-11-07 S. P. Rajaguru , Sarbani Basu , H. M. Antia

Where is the solar dynamo located and what is its modus operandi? These are still open questions in solar physics. Helio- and asteroseismology can help answer them by enabling us to study solar and stellar internal structures through global…

Solar and Stellar Astrophysics · Physics 2017-09-20 René Kiefer , Ariane Schad , Markus Roth

Strong magnetic fields are expected to significantly modify the pulsation frequencies of waves propagating in the cores of red giants or in the radiative envelopes of intermediate- and high-mass main-sequence stars. We calculate the g-mode…

Solar and Stellar Astrophysics · Physics 2024-09-24 Nicholas Z. Rui , J. M. Joel Ong , Stéphane Mathis

Magnetic fields in red giant stars remain a poorly understood topic, particularly in what concerns their intensity in regions far below the surface. In this work, we propose that gravity-dominated mixed modes of high absolute radial order…

Solar and Stellar Astrophysics · Physics 2020-07-21 Pedro Gomes , Ilídio Lopes

Recent observational results from asteroseismic studies show that an important fraction of solar-like stars do not present detectable stochastically excited acoustic oscillations. This non-detectability seems to correlate with a high…

Solar and Stellar Astrophysics · Physics 2025-07-30 Leïla Bessila , Adrien Deckx van Ruys , Valentin Buriasco , Stéphane Mathis , Lisa Bugnet , Rafael A. García , Savita Mathur

We rediscuss the evolutionary state of upper main sequence magnetic stars using a sample of Ap and Bp stars with accurate Hipparcos parallaxes and definitely determined longitudinal magnetic fields. FORS1 at the VLT in spectropolarimetric…

Astrophysics · Physics 2007-05-23 S. Hubrig , P. North , T. Szeifert