Related papers: Radial Mixing in Galactic Discs
The formation of thick stellar disks in spiral galaxies is studied. Simulations of gas-rich young galaxies show formation of internal clumps by gravitational instabilities, clump coalescence into a bulge, and disk thickening by strong…
A clear understanding of the chemical processing of matter, as it is transferred from a molecular cloud to a planetary system, depends heavily on knowledge of the physical conditions endured by gas and dust as these accrete onto a disk and…
We have investigated the possibilities to quantify how much stars move in the Milky Way stellar disk due to diffuse processes (i.e. so called blurring) and due to influences from spiral arms and the bar (i.e. so called churning). To this…
We review the current state of our knowledge concerning the rotation and angular momentum evolution of young stellar objects and brown dwarfs from a primarily observational view point. Periods are typically accurate to 1% and available for…
We demonstrate a significant difference in the angular momentum transport properties of galactic disks between regions in which the interstellar medium is single phase or two phase. Our study is motivated by observations of HI in extended…
This article first reviews the basic physics of rotating stars and their evolution. We examine in particular the changes of the mechanical and thermal equilibrium of rotating stars. An important (predicted and observed) effect is that…
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…
We examine the distribution of young stars associated with the spiral arms of a simulated L* cosmological disk galaxy. We find age patterns orthogonal to the arms which are not inconsistent with the predictions of classical density wave…
High-resolution, 2-D hydrodynamical simulations with a large dynamic range are performed to study the turbulent nature of the interstellar medium (ISM) in galactic disks. The simulations are global, where the self-gravity of the ISM,…
We propose that turbulent heating, wave pressure and gas exchanges between different regions of disks play a dominant role in determining the preferred, quasi-equilibrium, self-similar states of gas disks on large-scales. We present simple…
We investigate whether angular momentum transport due to unstable pulsation modes can play a significant role in the rotational evolution of massive stars. We find that these modes can redistribute appreciable angular momentum, and moreover…
We study the effect of angular momentum on the surface density profiles of disc galaxies, using high resolution simulations of major mergers whose remnants have downbending radial density profiles (type II). As described in the previous…
The radii of young (<100 Myr) star clusters correlate only weakly with their masses. This shallow relation has been used to argue that impulsive tidal perturbations, or `shocks', by passing giant molecular clouds (GMCs) preferentially…
The radial distribution of mass in a disk galaxy is strongly constrained by its rotation curve. The separate contributions from the individual stellar populations and dark matter (DM) are not easily disentangled, however, especially since…
We have recently shown that spiral density waves propagating in accretion disks can undergo a parametric instability by resonantly coupling with and transferring energy into pairs of inertial waves (or inertial-gravity waves when buoyancy…
The metal-poor gas continuously accreting onto the discs of spiral galaxies is unlikely to arrive from the intergalactic medium (IGM) with exactly the same rotation velocity as the galaxy itself and even a small angular momentum mismatch…
We study the dispersal of a gaseous disc surrounding a central high-mass stellar core once this circumstellar disc becomes fully ionized. If the stellar and surrounding EUV and X-ray radiations are so strong as to rapidly heat up and ionize…
Approximately half of all disc galaxies exhibit appreciable warps in both their stellar and HI discs. The typical warp amplitude is small (a few degrees), and only becomes noticeable at the periphery of the galaxy disc. As a result, warps…
This chapter reviews theoretical work on the stellar dynamics of galaxy disks. All the known collective global instabilities are identified, and their mechanisms described in terms of local wave mechanics. A detailed discussion of warps and…
Tidal encounters are believed to be one of the key drivers of galactic spiral structure in the Universe. Such spirals are expected to produce different morphological and kinematic features compared to density wave and dynamic spiral arms.…