Related papers: Tracing the Hercules stream around the Galaxy
The dynamics of stellar streams in rotating barred potentials is explained for the first time. Naturally, neighbouring stream stars reach pericentre at slightly different times. In the presence of a rotating bar, these neighbouring stream…
We examine the idea that dynamical parameters can be estimated by identifying locations in the solar neighbourhood where simulated velocity distributions match the observed local distribution. Here, the dynamical influence of both the…
Measurements of velocity and density perturbations along stellar streams in the Milky Way provide a time integrated measure of dark matter substructure at larger galactic radius than the complementary instantaneous inner halo strong lensing…
Co-moving groups of stars (streams) are well known in the velocity space of the disc near the Sun. Many are thought to arise from resonances with the Galactic bar or spiral arms. In this work, we search for similar moving groups in the…
In recent years several hypervelocity stars (HVSs) have been observed in the halo of our Galaxy. Such HVSs have possibly been ejected from the Galactic center and then propagated in the Galactic potential up to their current position. The…
Observational data indicate that the Milky Way is a barred spiral galaxy. Computation facilities and availability of data from Galactic surveys stimulate the appearance of models of the Galactic structure. More efforts to build dynamical…
Stars in the solar neighbourhood do not have a smooth distribution of velocities. Instead, the distribution of velocity components in the Galactic plane manifests a great deal of kinematic substructure. Here I present an analysis in…
Tidal stellar shells and streams are two of the most intriguing low-surface-brightness features within galaxies, consisting of stars accreted from satellite galaxies. A crucial ingredient in determining which type of feature will be formed…
The ultra-faint satellite galaxy Hercules has a strongly elongated and irregular morphology with detections of tidal features up to 1.3 deg (3 kpc) from its center. This suggests that Hercules may be dissolving under the Milky Way's…
Using photometry from Data Release 10 of the northern footprint of the Sloan Digital Sky Survey, we detect two new stellar streams with lengths of between $25\arcdeg$ and $50\arcdeg$. The streams, which we designate Hermus and Hyllus, are…
We have obtained high-resolution, high signal-to-noise spectra for 899 F and G dwarf stars in the Solar neighbourhood. The stars were selected on the basis of their kinematic properties to trace the thin and thick discs, the Hercules…
The Arcturus stream is an over-density of stars in velocity space and its origin has been much debated recently without any clear conclusion. Resolving the nature of the Arcturus stream can provide clues to the formation history of the…
During the past 20 years, numerous stellar streams have been discovered in both the Milky Way and the Local Group. These streams have been tidally torn from orbiting systems, which suggests that most of them should roughly trace the orbit…
We develop statistical methods for identifying star streams in the halo of the Milky Way galaxy that exploit observed spatial and radial velocity distributions. Within a great circle, departures of the observed spatial distribution from…
Using the potential-density phase shift approach developed by the present authors in earlier publications, we estimate the magnitude of radial mass accretion/excretion rates across the disks of six nearby spiral galaxies having a range of…
Galaxy models have long predicted that galactic bars slow down by losing angular momentum to their postulated dark haloes. When the bar slows down, resonance sweeps radially outwards through the galactic disc while growing in volume,…
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…
It has been recently shown that the halo near the Sun contains several kinematic substructures associated to past accretion events. For the more distant halo, there is evidence of large-scale density variations -- in the form of stellar…
We consider the process of stellar binaries tidally disrupted by a supermassive black hole. For highly eccentric orbits, as one star is ejected from the three-body system, the companion remains bound to the black hole. Hypervelocity stars…
The velocity distribution of nearby stars contains many "moving groups" that are inconsistent with the standard assumption of an axisymmetric, time-independent, and steady-state Galaxy. We study the age and metallicity properties of the…