Related papers: Transient spirals as superposed instabilities
Motivated by the recent results of \citet{Lesur_Ogilvie10} on the transport properties of incompressible convection in protoplanetary discs, in this paper we study the role of compressibility and hence of another basic mode -- spiral…
We present a new mechanism to explain the frequently observed and thus certainly permanent warping of spiral galaxies. We consider the possibility of non-linear coupling between the spiral wave of the galaxy and two warp waves, such that…
In recent years a handful of systems have been observed to show "negative" (nodal) superhumps, with periods slightly shorter than the orbital period. It has been suggested that these modes are a consequence of the slow retrograde precession…
Planet formation scenarios and the observed planetary dynamics in binaries pose a number of theoretical challenges, especially in what concerns circumbinary planetary systems. We explore the dynamical stirring of a planetesimal circumbinary…
Can the present dynamics of spiral galaxies tell us something about the merging history, the formation and evolution of disks? Galaxy interactions thicken or destroy disks; the simultaneous presence of thick and thin disks is a tracer of…
In the density wave theory of spiral structure, the grand-design two-armed spiral pattern is taken to rotate rigidly in a galactic disc with a constant, definite pattern speed. The observational measurement of the pattern speed of the…
We explore the hypothesis that a passing satellite or dark matter subhalo has excited coherent oscillations of the Milky Way's stellar disk in the direction perpendicular to the Galactic midplane. This work is motivated by recent…
We find that, under certain conditions, protoplanetary disks may spontaneously generate multiple, concentric gas rings without an embedded planet through an eccentric cooling instability. Using both linear theory and non-linear…
The properties and star formation processes in the far-outer disks of nearby spiral and dwarf irregular galaxies are reviewed. The origin and structure of the generally exponential profiles in stellar disks is considered to result from…
We explore the possibility that extended disks, such as that recently discovered in M31, are the result of a single dwarf (10^9--10^10 Msun) satellite merger. We carry out N-body simulations of dwarf NFW halos with embedded spheriodal…
The conservation of stellar actions is a fundamental assumption in orbit reconstruction studies in the Milky Way. However, the disc is highly dynamic, with time-dependent, non-axisymmetric features like transient spiral arms and giant…
Near the corotation resonance of a transient spiral arm, stellar orbital angular momenta may be changed without inducing significant kinematic heating, resulting in what has come to be known as radial migration. When radial migration is…
A one-armed spiral instability has been found to develop in differentially rotating stellar models that have a relatively stiff, $n=1$ polytropic equation of state and a wide range of rotational energies. This suggests that such…
The mean Galactocentric radial velocities $\langle v_{R}\rangle(R,\varphi)$ of luminous red giant stars within the mid-plane of the Milky Way reveal a spiral signature, which could plausibly reflect the response to a non-axisymmetric…
We explore a series expansion method to calculate the modes of oscillations for a variety of uniformly rotating finite disks, either with or without a dark halo. Since all models have the same potential, this survey focuses on the role of…
The rotation dynamics of spiral galaxies is modeled using a sum of two mass distributions: a spherical bulge and a thin disk. The density functions representing these mass distributions are calculated from the total angular momentum of the…
Recycled millisecond pulsars are susceptible to starquakes as they are continuously accreting matter from their binary companion. A starquake happens when the rotational frequency of the star crosses its breaking frequency. In this study,…
We introduce a novel type of surface waves that form at the edge of guiding structures consisting of several concentric rings. Such surface waves rotate steadily upon propagation and, in contrast to nonrotating waves, for high rotation…
We carry out three dimensional radiation hydrodynamical simulations of gravitationally unstable discs to explore the movement of mass in a disc following its initial fragmentation. We find that the radial velocity of the gas in some parts…
Observations of tidal disruption events (TDEs) on a timescale of years after the main flare show evidence of continued activity in the form of optical/UV emission, quasi-periodic eruptions, and delayed radio flares. Motivated by this, we…