Xing Wei

We performed a numerical study of the interaction of eccentricity tide and rotating convection in a spherical shell with the aim of understanding the dynamics of subsurface ocean in icy satellites. We find that the energy scaling exponent about buoyancy force (or tidal force) decreases with increasing tidal force (or buoyancy force). The combined tide-convection flow is not identical to superposition of two pure flows in respect of energy spectrum. Tide controls the large scale of fluid motion, but convection is important on a small scale, while the mode-mode transition occurs at an intermediate scale. Tide suppresses the heat transport efficiency and the dissipation of kinetic energy scales as the square of tidal force with a very weak dependence on the buoyancy force.

We study the Laplace surface of eccentric orbits around a Kerr black hole with a companion star. The relativistic Schwarzschild and Lense-Thirring precessions compete with the tidal torque from the companion. By solving the secular equations, we find that the two branches of equilibrium solutions exist only in a narrow range of orbital inclinations of test particle, and that stable equilibria are more readily found when the companion's obliquity approaches 90°. We then study the black hole effects on Lidov–Kozai cycles. In addition to the black hole suppression on cycle amplitude, we find that the cycle frequency is non-monotonic about distance from black hole and reaches its minimum in the transition between general relativistic (GR) apsidal precession and companion’s tidal precession. Finally, we use this mechanism to well interpret the nearly isotropic orientation of S-cluster in the Galactic Centre.

Calcium-aluminum-rich inclusions (CAIs) in carbonaceous chondritic meteorites are the oldest relics in the solar system. Notably, their radiogenic ages indicate a brief (100 kyr) condensation episode. In contrast, the reservoirs of the short-lived isotopes in CAIs, presumably supernovae or asymptotic giant stars, pollutes star-forming regions in giant molecular cloud complexes (GMC) over much longer (Myr) timescales. Through a series of numerical simulations, we show here the possibility that, within an extended region (~2–3 au), nearly all “presolar” CAI-loaded grains in the infalling clouds were sublimated and subsequently recondensed during the early (≲10 ⁵ yr) infall and formation phases of Class 0 disks. We adopt a set of initial conditions from a previous hydrodynamic simulation of GMC collapse and young stellar cluster formation. We analyze the evolution of the disk’s thermal distribution and dynamical structure resulting from the interaction between circumstellar disks and infalling gas. Our follow-up simulations, performed at much higher resolution, show significant and rapid changes in disk orientation and morphology due to the dynamic infall of external streamers. Warps and global spiral density waves commonly emerge, leading to intense dissipation that heats the gas to sufficiently high temperatures to sublimate prior-generation CAIs. This solid-to-gas phase transition is followed by subsequent cooling and recondensation. The CAIs contained in meteorites today may therefore be relics of the last major episode of infall onto Class 0 disks.

We provide a method to calculate the evolution of an eccentric and inclined orbit under the magnetic effect. Taking the unipolar interaction as an example, we study both coplanar and inclined orbits. We calculate the Lorentz force and then the changes in orbital energy and angular momentum. Combined with the total energy dissipation we write down the evolution equations of semimajor axis, eccentricity, inclination, and spin. This set of equations can be used to study the orbital and spin evolution under the magnetic interaction.

We provide a method to calculate the evolution of an eccentric and inclined orbit under the magnetic effect. Taking the unipolar interaction as an example, we study both coplanar and inclined orbits. We calculate the Lorentz force and then the changes in orbital energy and angular momentum. Combined with the total energy dissipation we write down the evolution equations of semi-major axis, eccentricity, inclination and spin. This set of equations can be used to study the orbital and spin evolution under the magnetic interaction.

We use a simple and straightforward method to derive the energy partition in magnetohydrodynamics (MHD) turbulence that was first studied by Lee and then more rigorously by Chandrasekhar. By investigating the energy equation, we find that the turbulent viscous and ohmic dissipations are comparable to each other. Under the condition that turbulent viscosity and turbulent magnetic diffusivity are comparable, we deduce that the ratio of kinetic to magnetic energies depends on the ratio of the turbulent magnetic length scale to turbulent velocity length scale of the largest eddies. When the two largest length scales are comparable, the two energies are in equipartition.

We use a simple and straightforward method to derive the energy partition in magnetohydrodynamics (MHD) turbulence that was first studied by Lee and then more rigorously by Chandrasekhar. By investigating the energy equation we find that the turbulent viscous and ohmic dissipations are comparable to each other. Under the condition that turbulent viscosity and turbulent magnetic diffusivity are comparable, we deduce that the ratio of kinetic to magnetic energies depends on the ratio of the turbulent magnetic lengthscale to turbulent velocity lengthscale of the largest eddies. When the two largest lengthscales are comparable, the two energies are in equipartition.

Observations from the Juno spacecraft show that Jupiter has a large dilute core rather than a compact core. To investigate the effects of different core structures on wave propagation and transmission in Jupiter's interior, we consider three models: (1) an isentropic sphere, (2) an isentropic envelope with a rigid core, and (3) an isentropic envelope with a dilute core. We study the propagation and transmission of p modes (sound waves), g modes (gravity waves), r modes (inertial waves), and GIWs (gravito-inertial waves) by solving the linear equations of a compressible, self-gravitating, uniformly rotating polytropic model, fully taking into account the the effects of Coriolis force but neglecting centrifugal flattening. Our results show that energy flux is primarily carried by fast waves with higher frequencies whereas kinetic energy by slow waves with lower frequencies. Rotation has a greater effect on non-axisymmetric modes than on axisymmetric ones. In model 2, rigid core facilitates propagation of r modes. In model 3, rotation enhances the transmission of GIWs across the interface between the dilute core and the isentropic envelope, particularly at high latitudes. This suggests that Jupiter's internal structure may be inferred by detecting the oscillation signals in its polar regions.

We study the internal wave propagation and transmission across the radiation-convection interface in a solar-type star by solving the linear perturbation equations of a self-gravitating and uniformly rotating polytropic fluid in spherical geometry with Coriolis force fully taken into account. Three structures are considered: convective zone, radiative zone, and a transitional layer at the interface. In a rotating convective zone, energy flux is predominantly carried by sound waves while kinetic energy by inertial waves, and rotation has a great effect on non-axisymmetric modes. In a radiative zone without rotation, energy flux is predominantly carried by sound waves or gravity waves while kinetic energy by gravity waves. In a layered structure, rotation enhances gravito-inertial waves transmission at the interface because the group velocity of inertial waves is almost along the rotational axis. This implies that we can detect the deep interior of rapidly rotating solar-type stars at the young age.

We study the internal wave propagation and transmission across the radiation-convection interface in a solar-type star by solving the linear perturbation equations of a self-gravitating and uniformly rotating polytropic fluid in spherical geometry with Coriolis force fully taken into account. Three structures are considered: convective zone, radiative zone, and a transitional layer at the interface. In a rotating convective zone, energy flux is predominantly carried by sound waves while kinetic energy by inertial waves, and rotation has a great effect on non-axisymmetric modes. In a radiative zone without rotation, energy flux is predominantly carried by sound waves or gravity waves while kinetic energy by gravity waves. In a layered structure, rotation enhances gravito-inertial waves transmission at the interface because the group velocity of inertial waves is almost along the rotational axis. This implies that we can detect the deep interior of rapidly rotating solar-type stars at the young age.