Related papers: Gaia 1 cannot be a Thick Disk Galactic cluster
We discuss recent observations of stars located close to the symmetry plane of the Milky Way, and examine them in the context of theories of Galaxy formation and evolution. The kinematics, ages, and compositions of thin disk stars in the…
As groups of coeval stars born from the same molecular cloud, an Open cluster (OC) is an ideal laboratory for studying the structure and dynamical evolution of the Milky Way. The release of High-Precision Gaia Early Data Release 3 (Gaia…
Context. Open clusters are very good tracers of the evolution of the Galactic disc. Thanks to Gaia, their kinematics can be investigated with an unprecedented precision and accuracy. Aims. The distribution of open clusters in the 6D phase…
The thickness of a galaxy's disk provides a valuable probe of its formation and evolution history. Observations of the Milky Way and local galaxies have revealed an ubiquitous disk structure with two distinctive components: an old thick…
We present preliminary results of an ongoing survey to probe the physical nature of a sample of open clusters (POCRs, Bica et al. 2001) believed to be in an advanced stage of dynamical evolution. This kind of object is very important to…
The differences in the relationships between the physical parameters and the chemical-element abundances in accreted globular star clusters and those formed inside the Galaxy have been investigated. The information on the supposed formation…
The origin of metal-rich, highly flattened, and rapidly rotating disk globular cluster system in the Galaxy is one of longstanding issues in the context of the Galaxy formation. Our numerical simulations suggest a new ``two-fold'' scenario…
Thanks to the recent wide-area photometric surveys, the number of star cluster candidates have risen exponentially in the last few years. Most detections, however, are based only on the presence of an overdensity of stars in a given region,…
[Abridged abstract] We have performed an abundance analysis for 176 F- and G- dwarfs of the Galactic thick disk component. Using accurate radial velocities combined with $Hipparcos$ astrometry, kinematics (U, V, and W) and Galactic orbital…
We study the kinematics of a local sample of stars, located within a cylinder of 500 pc radius centered on the Sun, in the RAVE dataset. We find clear asymmetries in the $v_R$-$v_\phi$ velocity distributions of thin and thick disk stars:…
Although thick stellar discs are detected in nearly all edge-on disc galaxies, their formation scenarios still remain a matter of debate. Due to observational difficulties, there is a lack of information about their stellar populations.…
In spite of the promise of new techniques for constraining the mass distribution in galaxy clusters, much remains to be learned from galaxy orbital velocities. This article reviews the theory of potential estimation in hot dynamical systems…
Disc galaxies show a large morphological diversity with varying contribution of three major structural components; thin discs, thick discs, and central bulges. Dominance of bulges increases with the galaxy mass (Hubble sequence) whereas…
$Context$. The assembly history experienced by the Milky Way is currently being unveiled thanks to the data provided by the $Gaia$ mission. It is likely that the globular cluster system of our Galaxy has followed a similarly intricate…
We show that the propagation of warps in gaseous disks can be strongly affected by compressional effects, when the thickness of the disk is taken into account. The physical reason is that, in realistic self-gravitating disks, the sound time…
The observations of bulge/disk segregation in the Universe are reviewed with a focus on whether the observed segregation in clusters is local or global, and whether there is bulge-disk segregation on large-scales. The high concentration of…
I analyse the projected density distribution of member stars over a wide area surrounding 18 Galactic globular clusters using the photometric and astrometric information provided by the second data release of the Gaia mission. A 5D mixture…
I review current theories of disk galaxy formation. All fail in the light of recent data for low surface brightness galaxies. The difficulty stems from the presence of a unique acceleration scale in the data.
The GAIA satellite will provide unprecedented phase-space information for our Galaxy and enable a new era of Galactic dynamics. We may soon see successful realizations of Galactoseismology, i.e., inferring the characteristics of the…
Open clusters are historically regarded as single-aged stellar populations representative of star formation within the Galactic disk. Recent literature has questioned this view, based on discrepant Na abundances relative to the field, and…