Related papers: A Spiral Structure in the Inner Oort Cloud
We present N-body simulations of globular clusters, in orbits around the Galaxy, in order to study quantitatively and geometrically the tidal effects they encounter. The clusters are modelised with multi-mass King-Michie models (Michie…
We review the most recent evidence for the amazing properties of the density distribution of dark matter around spiral galaxies. Their rotation curves, coadded according to the galaxy luminosity, conform to an universal profile which can be…
After a short review of the principal theories of spiral structure in galaxies, I describe two new developments. First, it now seems clear that linear theory cannot yield a full description for the development of spiral patterns because…
Spiral patterns in some disc galaxies have two arms in the centre, and three or more arms on the periphery. The same result is also obtained in numerical simulations of stellar and gaseous discs. We argue that such patterns may occur due to…
Gravitational instabilities can drive small-scale turbulence and large-scale spiral arms in massive gaseous disks under conditions of slow radiative cooling. These motions affect the observed disk morphology, its mass accretion rate and…
The classical picture that planet formation occurs in protoplanetary disks that are isolated from their environment is undergoing a major shift toward a more connected picture. An increasing amount of evolved disks are found to be actively…
Spiral density waves can arise in galactic disks as linear instabilities of the underlying stellar distribution function. Such an instability grows exponentially in amplitude at some fixed growth rate $\beta$ before saturating nonlinearly.…
We investigate the morphology and kinematics of the Galactic spiral structure based on a new sample of O- and early B-type stars. We select 6,858 highly confident OB star candidates from the combined data of the VST Photometric H$\alpha$…
Tidal debris from Galactic satellites generally forms one-dimensional elongated streams, since nearby Galactic orbits have almost identical frequency ratios. We show that the situation is different for orbits close to the Galactic disc,…
This article summarizes the structural parameters of the Galactic bulge and disk, and discusses the interpretation of the bulge microlensing observations and the determination of the Milky Way's luminous mass from the terminal velocity…
Context: Several spiral galaxies, as beautifully exhibited by the case of NGC 6946, display a prominent large-scale spiral structure in their gaseous outer disk. Such structure is often thought to pose a dynamical puzzle, because…
We present results concerning the internal structure and kinematics of disk galaxies formed in cosmologically motivated simulations. The calculations include dark matter, gas dynamics, radiative cooling, star formation, supernova feedback…
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.…
As a stellar group forms within its parent molecular cloud, new members first appear in the deep interior. These overcrowded stars continually diffuse outward to the cloud boundary, and even beyond. Observations have so far documented only…
The organization of the interstellar medium in disk galaxies obeys the large scale dynamics set by kpc-size structures. Improving our knowledge of how the dense, molecular gas is distributed in a disk is an important step in our…
The morphology and kinematics of the spiral structure of the Milky Way is a long-standing problem in astrophysics. In this review we firstly summarize various methods with different tracers used to solve this puzzle. The astrometry of…
The study of the internal structure of star clusters provides important clues concerning their formation mechanism and dynamical evolution. There are both observational and numerical evidences indicating that open clusters evolve from an…
We present Monte Carlo simulations of the dynamical evolution of the Oort cloud over the age of the Solar System, using an initial sample of one million test comets without any cloning. Our model includes perturbations due to the Galactic…
The thermal and chemical phases of the cool component of interstellar gas are discussed. Variations with galactocentric radius and from galaxy to galaxy are mostly the result of changes in the ambient interstellar pressure and radiation…
We consider a scenario of formation of the spiral structure in barred galaxies. This scenario includes the new non-resonant mechanism of elongation of spirals, due to the characteristic behaviour of the gravitational potential beyond the…