Related papers: Spatial Structure and Coherent Motion in Dense Pla…
The Kepler-discovered Systems with Tightly-packed Inner Planets (STIPs), typically with several planets of Earth to super-Earth masses on well-aligned, sub-AU orbits may host the most common type of planets, including habitable planets, in…
We present two-dimensional hydrodynamic simulations of self-gravitating protostellar disks subject to axisymmetric infall from envelopes and irradiation from the central star, to explore disk fragmentation due to gravitational instability…
In this paper we study the emergence of coherence in collective motion described by a system of interacting motiles endowed with an inner, adaptative, steering mechanism. By means of a nonlinear parametric coupling, the system elements are…
Gravitational coupling between planets and protoplanetary discs is responsible for many important phenomena such as planet migration and gap formation. The key quantitative characteristics of this coupling is the excitation torque density…
We investigate the linear axisymmetric viscous overstability in dense planetary rings with typical values of the dynamical optical depth $\tau\gtrsim 0.5$. We develop a granular flow model which accounts for the particulate nature of a…
In the conventional theory of planet formation, it is assumed that protoplanetary disks are axisymmetric and have a smooth radial profile. However, recent radio observations of protoplanetary disks have revealed that many of them have…
Astronomical observations reveal that protoplanetary disks around young stars commonly have ring- and gap-like structures in their dust distributions. These features are associated with pressure bumps trapping dust particles at specific…
In protoplanetary disks the aerodynamical friction between particles and gas induces a variety of instabilities that facilitate planet formation. Of these we examine the so-called `secular gravitational instability' (SGI) in the two-fluid…
The formation of a singularity in a compressible gas, as described by the Euler equation, is characterized by the steepening, and eventual overturning of a wave. Using a self-similar description in two space dimensions, we show that the…
We perform 3D SPH simulations of warped, non-coplanar gravitationally unstable discs to show that as the warp propagates through the self-gravitating disc, it heats up the disc rendering it gravitationally stable. Thus losing their spiral…
We present the numerical study of the formation of spiral structure in the context of violent relaxation. Initial conditions are the out-of-equilibrium disks of self-gravitating particles in rigid rotation. By that mechanism, robust and…
We consider collective dynamics of self-propelling particles in two dimensions. They can align themselves according to the direction of propulsion of their neighbours, together with a random perturbation (i.e. rotational fluctuation). They…
Growing planets interact with their surrounding protoplanetary disk, generating feedback effects that may promote or suppress nearby planet formation. We study how spiral waves launched by planets affect the motion and collisional evolution…
This paper constructs a theoretical framework for calculating the distribution of masses for secondary bodies forming via gravitational instability in the outer regions of circumstellar disks. We show that several alternate ways to specify…
The origin of spiral patterns in galaxies is still not fully understood. Similar features also develop readily in N-body simulations of isolated cool, collisionless disks, yet even here the mechanism has yet to be explained. In this series…
We will describe here the structure of singularity forming in gravitational collapse of spherically symmetric inhomogeneous dust. Such a collapse is described by the Tolman-Bondi-Lema{\^i}tre metric. The main new result here relates, in a…
Spiral density waves dominate several facets of accretion disc dynamics --- planet-disc interactions and gravitational instability (GI) most prominently. Though they have been examined thoroughly in two-dimensional simulations, their…
When particles move at a constant speed and have the tendency to align their directions of motion, ordered large scale movement can emerge despite significant levels of noise. Many variants of this model of self-propelled particles have…
We present results from large-scale particle simulations of the viscous overstability in Saturn's rings. The overstability generates a variety of structure on scales covering a few hundred metres to several kilometres, including…
Self-gravitational structure formation theory for astrophysics and cosmology is revised using nonlinear fluid mechanics. Gibson's 1996-2000 theory balances fluid mechanical forces with gravitational forces and density diffusion with…