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Recent work has shown that differential rotation, producing large scale drifts of fluid elements along stellar latitudes, is an unavoidable feature of r-modes in the nonlinear theory. We investigate the role of this differential rotation in…
Forming the Moon by a high-angular momentum impact may explain the Earth-Moon isotopic similarities, however, the post-impact angular momentum needs to be reduced by a factor of 2 or more to the current value (1 L_EM) after the Moon forms.…
A new mechanism is described, analyzed and visualized, for the dissipation of suprathermal rotation energy of molecules in magnetic fields, a necessary condition for their alignment. It relies upon the Lorentz force perturbing the motion of…
We present results concerning adiabatic inertial-mode oscillations of non-stratified superfluid neutron stars in Newtonian gravity, using the anelastic and slow-rotation approximations. We consider a simple two-fluid model of a superfluid…
We present a new model of time-dependent flow at low latitudes in the Earth's core between 2000 and 2018, derived from magnetic field measurements made on board the {\it Swarm} and CHAMP satellites and at ground magnetic observatories. The…
Evidence from seismic studies, mineral physics, thermal evolution models and geomagnetic observations is inconclusive about the presence of a stably stratified layer at the top of the Earth's fluid outer core. Such a convectively stable…
We perform numerical simulations of the TRAPPIST-1 system of seven exoplanets orbiting a nearby M dwarf, starting with a previously suggested stable configuration. The long-term stability of this configuration is confirmed, but the motion…
Detecting the Earth's inner core motions relative to the mantle presents a considerable challenge due to their indirect accessibility. Seismological observations initially provided evidence for differential/super-rotation of the inner core,…
We use a simple toy-model to discuss global MHD modes of a neutron star, taking into account the magnetic coupling between the elastic crust and the fluid core. Our results suggest that the notion of pure torsional crust modes is not useful…
Resonance, defined as the oscillation of a system when the temporal frequency of an external stimulus matches a natural frequency of the system, is important in both fundamental physics and applied disciplines. However, the spatial…
We investigate the oscillations of slowly rotating superfluid stars, taking into account the vortex mediated mutual friction force that is expected to be the main damping mechanism in mature neutron star cores. Working to linear order in…
Fluctuations and structure across a wide range of spatial and temporal scales are frequently studied in the solar wind. The properties of the low-frequency fluctuations are of relevance to turbulent energy injection into the plasma and the…
Internal redox reactions may irreversibly alter the mantle composition and volatile inventory of terrestrial and super-Earth exoplanets and affect the prospects for atmospheric observations. The global efficacy of these mechanisms, however,…
For a uniform population of neutron stars whose spin-down is dominated by the emission of gravitational radiation, an old argument of Blandford states that the expected gravitational-wave amplitude of the nearest source is independent of…
Motivated by the desire to understand the rich dynamics of precessionally driven flow in the liquid planetary core, we investigate, through numerical simulations, the precessing fluid motion in a rotating cylindrical annulus which possesses…
A Uranus orbiter would be well positioned to detect the planet's free oscillation modes, whose frequencies can resolve questions about Uranus's weakly constrained interior. We calculate the spectra that may manifest in resonances with ring…
We study the fully non-adiabatic tidal response of a uniformly rotating unevolved 20 Msun star to the dominant l=m=2 component of the companion's perturbing potential. This is done numerically with a 2D implicit finite difference scheme. We…
Star-planet tidal interactions may result in the excitation of inertial waves in the convective region of stars. Their dissipation plays a prominent role in the long-term orbital evolution of short-period planets. If the star is assumed to…
We simulate the nonlinear hydrodynamical evolution of tidally-excited inertial waves in convective envelopes of rotating stars and giant planets modelled as spherical shells containing incompressible, viscous and adiabatically-stratified…
Seismic mapping of the top of the inner core indicates two distinct areas of high P-wave velocity, the stronger one located beneath Asia, and the other located beneath the Atlantic. This two-fold pattern supports the idea that a…