Related papers: Observational Constraints on Disk Heating as a Fun…
Major mergers or/and the repeated minor mergers lead to dynamical heating of disks of galaxies. We analyze the available data on the velocity dispersion of stellar disks of S-S0 galaxies, including the new observational data obtained at 6m…
The velocity dispersion of nearby stars in the Galactic disc is well known to increase substantially with age; this is the so-called Age-Velocity relation, and is interpreted as a ``heating'' of the disc as a function of time. We have…
Vertically extended, high velocity dispersion stellar distributions appear to be a ubiquitous feature of disc galaxies, and both internal and external mechanisms have been proposed to be the major driver of their formation. However, it is…
We measure the shape of the velocity ellipsoid in two late-type spiral galaxies (Hubble types Sc and Scd) and combine these results with our previous analyses of six early-type spirals (Sa to Sbc) to probe the relation between galaxy…
We consider a differentially rotating, 2D stellar disk perturbed by two steady state spiral density waves moving at different patterns speeds. Our investigation is based on direct numerical integration of initially circular test-particle…
We consider a differentially rotating, 2D stellar disk perturbed by two steady state spiral density waves moving at different patterns speeds. Our investigation is based on direct numerical integration of initially circular test-particle…
We present the stellar and gaseous kinematics of an Sb galaxy, NGC 3223, with the aim of determining the vertical and radial stellar velocity dispersion as a function of radius, which can help to constrain disk heating theories. Together…
So far, six mechanisms have been proposed to account for the Galactic disk heating. Of these, the most important appear to be a combination of scattering of stars by molecular clouds and by spiral arms. We study a further mechanism, namely,…
The stellar velocity dispersion, $\sigma$, is a quantity of crucial importance for spiral galaxies, where it enters fundamental dynamical processes such as gravitational instability and disc heating. Here we analyse a sample of 34 nearby…
By making spectral absorption-line observations of disk galaxies at intermediate inclinations, we have been able to determine the amplitude of their constituent stars' random motions in three dimensions. This full measure of the shape of…
We develop an analytic model to calculate the rate at which galaxy disks are heated by dark matter substructures orbiting in their halos. The model takes into account the internal structure, mass function and accretion rate of satellites…
The stellar velocity ellipsoid (SVE) in galaxies can provide important information on the processes that participate in the dynamical heating of their disc components (e.g. giant molecular clouds, mergers, spiral density waves, bars).…
We use the marginal stability condition for galactic disks and the stellar velocity dispersion data published by different authors to place upper limits on the disk local surface density at two radial scalelengths $R=2h$. Extrapolating…
Disk galaxies evolve over time through processes that may rearrange both the radial mass profile and the metallicity distribution within the disk. This review of such slow changes is largely, though not entirely, restricted to…
The correlation between the maximum rotational velocity of the disk (v_m) and the central stellar velocity dispersion of the bulge (sigma) offers insights into the relationship between the halo and the bulge. We have assembled integrated H…
(Abridged) We analyze the evolution of 42 spiral galaxies in the Spitzer Infrared Nearby Galaxies Survey, using extinction-corrected UV, optical and near-infrared radial profiles to probe the emission of stars of different ages as a…
Observations of turbulent velocity dispersions in the HI component of galactic disks show a characteristic floor in galaxies with low star formation rates and within individual galaxies the dispersion profiles decline with radius. We carry…
Frankel et al (2020) reported that the rate of diffusion in angular momentum by stars in the disk of the Milky Way was about ten times faster than the rate of heating, which places a stringent requirement on the nature of disk star…
Various processes have been proposed to explain how galaxy discs acquire their thickness. A simple diagnostic for ascertaining this ``heating'' mechanism is provided by the ratio of the vertical to radial velocity dispersion components. In…
In the solar-neighbourhood, older stars have larger random velocities than younger ones. It is argued that the increase in velocity dispersion with time is predominantly a gradual process rather than one induced by discrete events such as…