We present a calculation of the sedimentation of grains in a giant gaseous protoplanet such as that resulting from a disk instability of the type envisioned by Boss (1998). Boss (1998) has suggested that such protoplanets would form cores through the settling of small grains. We have tested this suggestion by following the sedimentation of small silicate grains as the protoplanet contracts and ...

Virial theorem is important for understanding stellar structures. It produces an interesting connection between magnetic and gravitational energies. Using the general form of the virial theorem including the magnetic field (toroidal magnetic field), we may explain the solar dynamo model in relation to variations of the magnetic and gravitational energies. We emphasize the role of the gravitatio...

Wintertime convective mixing plays a pivotal role in the sub-polar North Atlantic spring phytoplankton blooms by favoring phytoplankton survival in the competition between light-dependent production and losses due to grazing and gravitational settling. We use satellite and ocean reanalyses to show that the area-averaged maximum winter mixed layer depth is positively correlated with April chloro...

Metal abundances are the indicators of the chemical evolution in white dwarfs, which is dominated by the element separation due to the strong gravitational field. A reliable analysis and interpretation requires high resolution and high signalto-noise UV spectroscopy. For hot helium rich DO white dwarfs this is currently only feasible with the Hubble Space Telescope. In this paper I report on ou...

The initial stages of planet formation in circumstellar gas discs proceed via dust grains that collide and build up larger and larger bodies1. How this process continues from metre-sized boulders to kilometre-scale planetesimals is a major unsolved problem2: boulders stick together poorly3, and spiral into the protostar in a few hundred orbits due to a head wind from the slower rotating gas4. G...

We investigate the combined effects of gravity, attractive interactions, and brownian motion in suspensions of colloidal particles and nonadsorbing polymer. Depending on the effective strength of gravitational forces, resulting from a density mismatch between the colloids and the solvent, and the magnitude and range of the depletion interactions induced by the polymer, sedimentation in these su...