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We compare different gravitational-wave extraction methods used in three-dimensional nonlinear simulations against linear simulations of perturbations of spherical spacetimes with matter. We present results from fully general-relativistic…

General Relativity and Quantum Cosmology · Physics 2015-03-13 Sebastiano Bernuzzi , Luca Baiotti , Giovanni Corvino , Roberto De Pietri , Alessandro Nagar

We consider the amplification and transport of a magnetic field in the collapsed core of a massive star, including both the region between the neutrinosphere and the shock, and the central, opaque core. An analytical argument explains why…

Astrophysics · Physics 2009-11-06 Christopher Thompson , Norman Murray

Convection plays a central role in the dynamics of any stellar interior, and yet its operation remains largely-hidden from direct observation. As a result, much of our understanding concerning stellar convection necessarily derives from…

Solar and Stellar Astrophysics · Physics 2016-02-17 Nicholas A. Featherstone , Bradley W. Hindman

An improved treatment of neutrino oscillations follows when neutrino mass eigenstates and their associated recoiling particle states are entangled. When the neutrino and its recoil partner are treated as a single entangled quantum state the…

High Energy Physics - Phenomenology · Physics 2015-02-03 R. G. Hamish Robertson

Convection occurs ubiquitously on and in rotating geophysical and astrophysical bodies. Prior spherical shell studies have shown that the convection dynamics in polar regions can differ significantly from the lower latitude, equatorial…

Fluid Dynamics · Physics 2023-01-18 T. Gastine , J. M. Aurnou

Internal waves propagating in stellar radiative zones can lead to efficient angular momentum transport, that should occur throughout the whole lifetime of stars. They thus play a key role in shaping the internal rotation profile of these…

Solar and Stellar Astrophysics · Physics 2018-11-08 Q. André , S. Mathis , L. Amard

Evolved stars dominate galactic spectra, enrich the galactic medium, expand to change their planetary systems, eject winds of a complex nature, produce spectacular nebulae and illuminate them, and transfer material between binary…

We present a three-dimensional model of rotating convection combined with a simplified corona in spherical coordinates. The motions in the convection zone generate a large-scale magnetic field that gets sporadically ejected into the outer…

Solar and Stellar Astrophysics · Physics 2012-07-17 Jörn Warnecke , Petri J. Käpylä , Maarit. J. Mantere , Axel Brandenburg

We model a coronal loop as a three-dimensional magnetic cylinder in a realistic solar atmosphere that extends from the chromosphere to the corona. Kink oscillations, believed ubiquitous in the solar corona, are launched in the loop. Heating…

Solar and Stellar Astrophysics · Physics 2023-05-31 Mingzhe Guo , Timothy Duckenfield , Tom Van Doorsselaere , Konstantinos Karampelas , Gabriel Pelouze , Yuhang gao

A simplified model for stellar and planetary convection is derived for the magnitude of the rms velocity, degree of superadiabaticity, and characteristic length scale with Rossby number as well as with thermal and viscous diffusivities.…

Solar and Stellar Astrophysics · Physics 2018-11-13 Kyle Augustson , Stéphane Mathis

We report for the first time on triadic resonances in a rotating convection system. Using direct numerical simulations, we find that convective modes in a rotating spherical fluid can excite a pair of inertial modes whose frequencies and…

Fluid Dynamics · Physics 2020-12-30 Yufeng Lin

We present an analytical study of the effect of small convective cores on the oscillations of solar-like pulsators. Based on an asymptotic analysis of the wave equation near the center of the star, we derive an expression for the…

Astrophysics · Physics 2009-06-23 M. S. Cunha , T. S. Metcalfe

In literature, it is often said that a uniform circular array (UCA) composed of a sufficient number of radiating elements is able to generate a vortex wave with arbitrary topological charge. While providing a very simple and intuitive…

Classical Physics · Physics 2019-09-17 Andrea Cagliero

We use time-evolutions of the linear perturbation equations to study the oscillations of rapidly rotating neutrons stars. Our models account for the buoyancy due to composition gradients and we study, for the first time, the nature of the…

Astrophysics · Physics 2009-11-13 A. Passamonti , B. Haskell , N. Andersson , D. I. Jones , I. Hawke

A simple model of a spherically symmetric, pulsating star is calculated. The application to the Sun gives a 166-min radial pulsation. The theory of gravitation in flat space-time implies for a spherically symmetric, nonstationary star small…

General Physics · Physics 2010-02-09 Walter Petry

We find significant fluctuations of angular momentum within the convective helium shell of a pre-collapse massive star - a core-collapse supernova progenitor - which may facilitate the formation of accretion disks and jets that can explode…

Solar and Stellar Astrophysics · Physics 2016-08-17 Avishai Gilkis , Noam Soker

We consider the role of centrifugal force on the energetics of electrons moving along the magnetic field lines of spinning active galactic nuclei. We find the energy gained by charged particles against inverse Compton scattering and/…

Astrophysics · Physics 2007-05-23 R. T. Gangadhara , H. Lesch

Solar-like oscillations are excited stochastically by convection. They occur in stars with an outer convection zone, which includes the Sun and other stars on the lower main sequence, as well as cool subgiants and red giants. This chapter…

Solar and Stellar Astrophysics · Physics 2011-07-12 Timothy R. Bedding

Electric charge neutrality in a compact star provides an important relation- ship between the chiral dynamics and neutrino propagation in the star. Since the sudden drop of the electron density at the critical point of the first-order…

Astrophysics · Physics 2015-06-24 Chengfu Mu , Gaofeng Sun , Pengfei Zhuang

How much energy does it take to stamp a thin elastic shell flat? Motivated by recent experiments on the wrinkling patterns of floating shells, we develop a rigorous method via $\Gamma$-convergence for answering this question to leading…

Analysis of PDEs · Mathematics 2021-02-17 Ian Tobasco