Related papers: Disc fragmentation rarely forms planetary-mass obj…
It has already been shown, using a local model, that accretion discs with cooling times t_cool <= 3 Omega^-1 fragment into gravitationally bound objects, while those with cooling times t_cool > 3 Omega^-1 evolve into a quasi-steady state.…
We develop a semi-analytical model for computing planetary system formation with the aim of explaining the observed diversity of planetary systems architectures and relate this primordial diversity with the initial properties of the disc…
We investigate the formation of discs within binary systems where at least one component has left the main sequence. In particular we calculate the occurrence rates of systems which can host long-lived, massive discs that may be able to…
We have performed three-dimensional two-fluid (gas-dust) hydrodynamical models of circumstellar discs with embedded protoplanets (3 - 333 M\oplu) and small solid bodies (radii 10cm to 10m). We find that high mass planets (\gtrsim Saturn…
The formation of gas-giant planets within the lifetime of a protoplanetary disk is challenging especially far from a star. A promising model for the rapid formation of giant-planet cores is pebble accretion in which gas drag during…
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…
Planets are thought to form via accretion from a remnant disk of gas and solids around a newly formed star. During this process material in the disk either remains bound to the star as part of either a planet, a smaller celestial body, or…
In recent years, many wide orbit circumbinary giant planets have been discovered; some of these may have formed by gravitational fragmentation of circumbinary discs. The aim of this work is to investigate the lower mass limit for…
Since 1995, more than 500 exoplanets have been detected using different techniques, of which 11 were detected with gravitational microlensing. Most of these are gravitationally bound to their host stars. There is some evidence of…
The observation of massive exoplanets at large separation from their host star, like in the HR 8799 system, challenges theories of planet formation. A possible formation mechanism involves the fragmentation of massive self-gravitating discs…
Estimates of the frequency of planetary systems in the Milky Way are observationally limited by the low-mass planet regime. Nevertheless, substantial evidence for systems with undetectably low planetary masses now exist in the form of…
Isolated low-mass stars are formed, in the standard picture, from the collapse of dense cores condensed out of strongly magnetized molecular clouds. The dynamically collapsing inflow traps nearly half of the critical magnetic flux needed…
The surroundings of massive protostars constitute an accretion disc which has numerically been shown to be subject to fragmentation and responsible for luminous accretion-driven outbursts. Moreover, it is suspected to produce close binary…
We review the role of stellar flybys and encounters in shaping planet-forming discs around young stars, based on the published literature on this topic in the last 30 years. Since most stars $\leq~2$ Myr old harbour protoplanetary discs,…
Protoplanetary discs are crucial to understanding how planets form and evolve, but these objects are subject to the vagaries of the birth environments of their host stars. In particular, photoionising radiation from massive stars has been…
Planets are born from disks of gas and dust, and observations of protoplanetary disks are used to constrain the initial conditions of planet formation. However, dust mass measurements of Class II disks with ALMA have called into question…
We carry out three dimensional radiation hydrodynamical simulations of gravitationally unstable discs using to explore the movement of mass in a disc following its fragmentation. Compared to a more quiescent state before it fragments, the…
We investigate the migration of massive extrasolar planets due to gravitational interaction with a viscous protoplanetary disc. We show that a model in which planets form at 5 AU at a constant rate, before migrating, leads to a predicted…
Gravitational instability has been invoked as a possible mechanism of giant planet formation in protoplanetary disks. Here we critically revise its viability by noting that for the direct production of giant planets it is not enough for…
Protoplanetary disks dissipate rapidly after the central star forms, on time-scales comparable to those inferred for planet formation. In order to allow the formation of planets, disks must survive the dispersive effects of UV and X-ray…