Related papers: Comments on the "Monoceros" affair
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…
Aims. Galaxy mass models based on simple and analytical functions for the density and potential pairs have been widely proposed in the literature. Disk models constrained by kinematic data alone give information on the global disk structure…
We re-examine the age-velocity dispersion relation in the solar neighborhood using improved stellar age estimates that are based on Hipparcos parallaxes and recent stellar evolution calculations. The resulting relation shows that the Milky…
The origin of the Galactic halo stellar structure known as the Monoceros ring is still under debate. In this work, we study that halo substructure using deep CFHT wide-field photometry obtained for the globular clusters NGC2419 and…
The nucleus of M31 may be a thick eccentric disk, composed of stars traveling on nearly Keplerian orbits around a black hole or other dark compact object. This hypothesis reproduces most of the features seen in HST photometry of the center…
Near-field observations may provide tight constraints - i.e. "boundary conditions" - on any model of structure formation in the Universe. Detailed observational data have long been available for the Milky Way (e.g. Freeman $\&$…
Accurate characterization of thick disc properties from recent kinematic and photometric surveys provides converging evidences that this intermediate population is a sequel of the violent heating of early disc populations by a merging…
The Local Group member M33 is a pure disk galaxy bearing no prominent bulge or stellar halo. It constitutes a challenge for any hierarchical galaxy formation theory and an ideal laboratory for studying quiescent star formation. Using…
Our Milky Way Galaxy is a typical large spiral galaxy, representative of the most common morphological type in the local Universe. We can determine the properties of individual stars in unusual detail, and use the characteristics of the…
We have recently identified a previously unknown radial migration mechanism resulting from the overlap of spiral and bar resonances in galactic discs (Minchev & Famaey 2010, Minchev et al. 2010). This new mechanism is much more efficient…
We compare both the Milky Way and M31 to local external disk galaxies within the same mass range, using their relative locations in the planes formed by Vflat vs. MK (the Tully-Fisher relation), j_disk (specific angular momentum) and the…
The spatial, kinematic, and elemental-abundance structure of the Milky Way's stellar disk is complex, and has been difficult to dissect with local spectroscopic or global photometric data. Here, we develop and apply a rigorous density…
The light distribution in the disks of many galaxies is non-axisymmetric or `lopsided' with a spatial extent much larger along one half of a galaxy than the other, as in M101. Recent near-IR observations show that lopsidedness is common.…
Observations of massive stars within the central parsec of the Galaxy show that, while most stars orbit within a well-defined disc, a significant fraction have large eccentricities and / or inclinations with respect to the disc plane. Here,…
Observations reveal that mature spiral galaxies consist of stars, gases and plasma approximately distributed in a thin disk of circular shape, usually with a central bulge. The rotation velocities quickly increase from the galactic center…
In previous galactic dynamo theories of the origin of the magnetic field in our galaxy, the subject of flux-freezing has been omitted. As a consequence, the equation of mass flow has generally also been omitted, particularly in the halo…
A critical discussion of our knowledge about extragalactic cosmic rays and magnetic fields is attempted. What do we know for sure? What are our prejudices? How do we confront our models with the observations? How can we assess the…
The dominant physical processes responsible for the formation and longevity of giant gaseous and stellar discs in galaxies remain controversial. Although they are rare (less than 10 confirmed as of now), giant low-surface brightness (gLSB)…
The diffuse light within galaxy groups and clusters provides valuable insight into the growth of massive cosmic structures. Groups are particularly interesting in this context, because they represent the link between galactic haloes and…
I discuss various proposed formation scenarios for the metal-poor components of the Milky Way Galaxy, emphasising the stellar halo and the thick disk. Interactions and accretion played a significant role in Galactic evolution, in particular…