Parametric instability in a free-evolving warped protoplanetary disc

Magnetorotational instability in protoplanetary discs

We investigate the linear growth and vertical structure of the magnetorotational instability (MRI) in weakly ionised, stratified accretion discs. The magnetic field is initially vertical and dust grains are assumed to have settled towards the midplane, so charges are carried by electrons and ions only. Solutions are obtained at representative radial locations from the central protostar for diff...

Moduli Instability in Warped Compactification

We derive four-dimensional effective theories for warped compactification of the tendimensional IIB supergravity. We show that these effective theories allow a much wider class of solutions than the original higher-dimensional theories. This result indicates that the effective four-dimensional theories should be used with caution, if one regards the higher-dimensional theories more fundamental.

Face-on accretion onto a protoplanetary disc

Context. Stars are generally born in clustered stellar environments, which can affect their subsequent evolution. An example of this environmental influence can be found in globular clusters (GCs) harbouring multiple stellar populations. Bastian et al. recently suggested an evolutionary scenario in which a second (and possibly higher order) population is formed by the accretion of chemically en...

Gravitational instability in binary protoplanetary disks

We review the models and results of simulations of self-gravitating, gaseous protoplanetary disks in binary star systems. These models have been calculated by three different groups with three different computational methods, two particle-based and one grid-based. We show that interactions with the companion star can affect the temperature distribution and structural evolution of disks, and dis...

Synchrotron-betatron parametric instability in free-electron lasers.