In its first part, this paper summarizes recent work on the mass and shape of the Galactic dark halo. The second part presents a review of the large-scale structure of the Milky Way, and of the evidence that the inner Galaxy is dominated by baryonic matter. This is briefly compared with the predictions of ΛCDM and MOND. Finally, a summary is given of bulge formation from clumpy, gas-rich disks,...

We study the gravitational lensing effects of spiral galaxies by taking a model of the Milky Way and computing its lensing properties. The model is composed of a spherical Hernquist bulge, a Miyamoto-Nagai disc and an isothermal halo. As a strong lens, a spiral galaxy like the Milky Way can give rise to four different imaging geometries. They are (i) three images on one side of the galaxy centr...

Isotope ratios have opened a new window into the study of the details of stellar evolution, supernovae, and galactic chemical evolution. We present the evolution of the isotope ratios of elemental abundances (from C to Zn) in the solar neighbourhood, bulge, halo, and thick disk, using chemical evolution models with updated yields of Asymptotic Giant Branch (AGB) stars and core-collapse supernov...

We review the origin and evolution of the heavy elements, those with atomic numbers greater than 30, in the early history of the Milky Way. There is a large star-to-star bulk scatter in the concentrations of heavy elements with respect to the lighter metals, which suggests an early chemically unmixed and inhomogeneous Galaxy. The relative abundance patterns among the heavy elements are often ve...

We have obtained VLA and optical follow-up observations of the low-velocity H I source HIZSS 3 discovered by Henning et al. 2000 and Rivers 2000 in a survey for nearby galaxies hidden by the disk of the Milky Way. Its radio characteristics are consistent with this being a nearby (∼ 1.8 Mpc) low-mass dwarf irregular galaxy (dIm). Our optical imaging failed to reveal a resolved stellar population...

We look for observational signatures that could discriminate between Newtonian and modified Newtonian (MOND) dynamics in the Milky Way, in view of the advent of large astrometric and spectroscopic surveys. Indeed, a typical signature of MOND is an apparent disk of “phantom” dark matter, which is uniquely correlated with the visible disk-density distribution. Due to this phantom dark disk, Newto...

The simplest interpretation of the microlensing events towards the Large Magellanic Cloud detected by the MACHO and EROS collaborations is that about one third of the halo of our own Milky Way galaxy exists in the form of objects of around 0.5 solar mass. There are grave problems with this interpretation. A normal stellar population of 0.5 solar mass stars should be visible. The other obvious c...

The Milky Way is often considered to be the best example of a spiral for which the dark matter not only dominates the outer kinematics, but also plays a major dynamical role in the inner galaxy: the Galactic disk is therefore said to be " sub-maximal. " This conclusion is important to the understanding of the evolution of galaxies and the viability of particular dark matter models. The Galactic...

We used the Wide Field Planetary Camera 2 aboard the Hubble Space Telescope to search for globular clusters in the inner regions of the nearby giant elliptical galaxy NGC 5128. This galaxy is believed to be the product of a merger between a large elliptical galaxy and a small late-type spiral between 160 and 500 Myr ago. We identified 21 globular cluster candidates and measured their core radii...