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Rapid orbital drift of macroscopic dust particles is one of the major obstacles against planetesimal formation in protoplanetary disks. We reexamine this problem by considering porosity evolution of dust aggregates. We apply a porosity…
Context. This is the fourth paper in a series showing the results of planet population synthesis calculations. Aims. Our goal in this paper is to systematically study the effects of important disk properties, namely disk metallicity, mass…
In protoplanetary discs, the coagulation of dust grains into large aggregates still remains poorly understood. Grain porosity appears to be a promising solution to allow the grains to survive and form planetesimals. Furthermore, dust…
Context: Protoplanetary disks are observed to remain dust-rich for up to several million years. Theoretical modeling, on the other hand, raises several questions. Firstly, dust coagulation occurs so rapidly, that if the small dust grains…
Axisymmetric dust rings containing tens to hundreds of Earth masses of solids have been observed in protoplanetary discs with (sub-)millimetre imaging. Here, we investigate the growth of a planetary embryo in a massive (150M$_\oplus$)…
We reconsider the commonly held assumption that warm debris disks are tracers of terrestrial planet formation. The high occurrence rate inferred for Earth-mass planets around mature solar-type stars based on exoplanet surveys (roughly 20%)…
When a planet forms a deep gap in a protoplanetary disk, dust grains cannot pass through the gap. As a consequence, the density of the dust grains can increase up to the same level of the density of the gas at the outer edge. The feedback…
It is difficult to imagine a planet formation model that does not at some stage include a gravitationally unstable disc. Initially unstable gas-dust discs may form planets directly, but the high surface density required has motivated the…
The leading theory for the formation of the Earth's moon invokes a collision between a Mars-sized body and the proto-Earth to produce a disk of orbiting material that later condenses to form the Moon. Here we study the early evolution of…
We investigate the linear growth and vertical structure of the MRI in protoplanetary discs when dust grains are well mixed with the gas over the entire disc thickness. All the grains have the same radius (a = 0.1, 1 or 3 micron) and…
Direct imaging observations of planets revealed that wide-orbit ($>10$ au) giant planets exist even around subsolar-metallicity host stars and do not require metal-rich environments for their formation. A possible formation mechanism of…
One of many challenges in forming giant gas planets via Gravitational disc Instability model (GI) is an inefficient radiative cooling of the pre-collapse fragments. Since fragment contraction times are as long at $10^5 -10^7$ years, the…
Debris disks or exo-Kuiper belts, detected through their thermal or scattered emission from their dusty components, are ubiquitous around main-sequence stars. Since dust grains are short-lived, their sustained presence is thought to require…
Disc-driven planet migration is integral to the formation of planetary systems. In standard, gas-dominated protoplanetary discs, low-mass planets or planetary cores undergo rapid inwards migration and are lost to the central star. However,…
Recent detailed observations of protoplanetary discs revealed a lot of sub-structures which are mostly ring-like. One interpretation is that these rings are caused by growing planets. These potential planets are not yet opening very deep…
The Rosseland mean opacity of dust in protoplanetary disks is often calculated assuming the interstellar medium (ISM) size distribution and a constant dust-to-gas ratio. However, the dust size distribution and the dust-to-gas ratio in…
We have conducted the first comprehensive numerical investigation of the relative velocity distribution of dust particles in self-gravitating protoplanetary discs with a view to assessing the viability of planetesimal formation via direct…
Rocky asteroids and planets display nucleosynthetic isotope variations that are attributed to the heterogeneous distribution of stardust from different stellar sources in the solar protoplanetary disk. Here we report new high precision…
We address two outstanding issues in the sequential accretion scenario for gas giant planet formation, the retention of dust grains in the presence of gas drag and that of cores despite type I migration. The efficiency of these processes is…
Collisions of mm-size dust aggregates play a crucial role in the early phases of planet formation. We developed a laboratory setup to observe collisions of dust aggregates levitating at mbar pressures and elevated temperatures of 800 K. We…