Related papers: Primordial planet spin driven by boundary layer ef…
Be stars are rapidly rotating, with angular frequency around $0.7-0.8$ of their Keplerian break up frequency, as a result of significant accretion during the earlier stellar evolution of a companion star. Material from the equator of the Be…
Gas giant planets are expected to accrete most of their mass via a circumplanetary disk. If the planet is unmagnetized and initially slowly rotating, it will accrete gas via a radially narrow boundary layer and rapidly spin up. Radial…
Planetesimal accretion during planet formation is usually treated as collisionless. Such accretion from a uniform and dynamically cold disk predicts protoplanets with slow retrograde rotation. However, if the building blocks of…
An analytic model is developed for the erosion of protoplanetary gas discs by high velocity magnetized stellar winds. The winds are centrifugally driven from the surface of rapidly rotating, strongly magnetized young stars. The presence of…
Over 50 circumbinary exoplanets have been discovered in recent years, with several of them being gas giants on wide orbits ($>10$AU). The aim of this work is to investigate whether these planets can form through circumbinary disc…
The origin of the spins of giant planets is an open question in astrophysics. As planets and stars accrete from discs, if the specific angular momentum accreted corresponds to that of a Keplerian orbit at the surface of the object, it is…
Abridged: We use three-dimensional SPH simulations to investigate the collapse of low-mass prestellar cores and the formation and early evolution of protostellar discs. The initial conditions are slightly supercritical Bonnor-Ebert spheres…
The formation of a circumplanetary disk and accretion of angular momentum onto a protoplanetary system are investigated using 3D hydrodynamical simulations. The local region around a protoplanet in a protoplanetary disk is considered with…
Detached circumplanetary disks are unstable to tilting as a result of the stellar tidal potential. We examine how a tilted circumplanetary disk affects the evolution of the spin axis of an oblate planet. The disk is evolved using…
We study protoplanetary disc evolution assuming that angular momentum transport is driven by gravitational instability at large radii, and magnetohydrodynamic (MHD) turbulence in the hot inner regions. At radii of the order of 1 AU such…
The formation of protoplanetary discs during the collapse of molecular dense cores is significantly influenced by angular momentum transport, notably by the magnetic torque. In turn, the evolution of the magnetic field is determined by…
We investigate the spin state of a protoplanet during the pebble accretion influenced by the gas flow in the gravitational potential of the protoplanet and how it depends on the planetary mass, the headwind speed, the distance from the host…
We study the interaction between massive planets and a gas disc with a mass in the range expected for protoplanetary discs. We use SPH simulations to study the orbital evolution of a massive planet as well as the dynamical response of the…
We develop equations and obtain solutions for the structure and evolution of a protodisc region that is initially formed with no radial motion and super-Keplerian rotation speed when wind material from a hot rotating star is channelled…
Planets form in protoplanetary discs. Their masses, distribution, and orbits sensitively depend on the structure of the protoplanetary discs. However, what sets the initial structure of the discs in terms of mass, radius and accretion rate…
We carry out global three-dimensional radiation hydrodynamical simulations of self-gravitating accretion discs to determine if, and under what conditions, a disc may fragment to form giant planets. We explore the parameter space (in terms…
The migration of planets plays an important role in the early planet-formation process. An important problem has been that standard migration theories predict very rapid inward migration, which poses problems for population synthesis…
With hundreds of exoplanets detected, it is necessary to revisit giant planets accretion models to explain their mass distribution. In particular, formation of sub-jovian planets remains unclear, given the short timescale for the runaway…
We discuss the factors influencing the formation and gravitational fragmentation of protostellar discs. We start with a review of how observations of prestellar cores can be analysed statistically to yield plausible initial conditions for…
Massive giant planets, such as the ones being discovered by direct imaging surveys, likely experience the majority of their growth through a circumplanetary disc. We argue that the entropy of accreted material is determined by boundary…