Related papers: Kinematic Decoupling of Globular Clusters with Ext…
Horizontal Branch stars belong to an advanced stage in the evolution of the oldest stellar galactic population, occurring either as field halo stars or grouped in globular clusters. The discovery of multiple populations in these clusters,…
Central galaxies (CGs) in galaxy groups and clusters are believed to form and assemble a good portion of their stellar mass at early times, but they also accrete significant mass at late times via galactic cannibalism, that is merging with…
We analyse complementary HST and SUBARU data for the globular cluster NGC 2419. We make a detailed analysis of the horizontal branch (HB), that appears composed by two main groups of stars: the luminous blue HB stars ---that extend by…
Context. Many Milky Way globular clusters (GCs) host multiple stellar populations, challenging the traditional view of GCs as single-population systems. It has been suggested that second-generation stars could form in a disk from gas lost…
The location of Galactic Globular Clusters' (GC) stars on the horizontal branch (HB) should mainly depend on GC metallicity, the "first parameter", but it is actually the result of complex interactions between the red giant branch (RGB)…
Recent developments relevant to the formation of globular cluster systems in galaxies are discussed, including (1) The age distribution of the oldest Milky Way clusters, (2) Subgroups and possible accretion and merger remnants in the…
The observed abundance variations in globular cluster red giants indicate that these stars may be mixing helium from the hydrogen shell outward into the envelope, presumably as a result of internal rotation. We have investigated the…
We use a series of high-resolution simulations of a `Milky-Way' halo coupled to semi-analytic methods to study the formation of our own Galaxy and of its stellar halo. The physical properties of our model Milky Way, as well as the age and…
Currently only a small number of Milky Way (MW) stars are known to exist beyond 100 kpc from the Galactic center. Though the distribution of these stars in the outer halo is believed to be sparse, they can provide evidence of more recent…
We have studied the system of globular clusters (GCs) that formed in other galaxies and eventually accreted onto the Milky Way. Thus, the samples of GCs belonging to different tidal streams, obtained on the basis of the latest data from the…
We review the properties of globular clusters which make them useful for studying the Galactic halo, Galactic chemical evolution, and the early stages of the formation of the Milky Way. We review the evidence that GCs have a chemical…
The horizontal branch (HB) morphology of globular clusters (GCs) is mainly determined by metallicity. However, the fact that GCs with almost the same metallicity exhibit different HB morphologies demonstrates that at least one more…
Observations have argued that Milky Way (MW), Andromeda, and lower-mass galaxies exhibit extended soft X-ray diffuse halos to radii $R\gtrsim100\,$kpc in the circumgalactic medium (CGM). If interpreted as thermal emission, the shallow…
The two red clumps (RCs) observed in the color-magnitude diagram of the Milky Way bulge is widely accepted as evidence for an X-shaped structure originated from the bar instability. A drastically different interpretation has been suggested,…
In this paper we address the issue of the origin of some observational properties of the galactic globular cluster system. After a preliminary study of some general properties of the main evolutionary processes, we investigate the evolution…
Helium variations are common features of globular clusters (GCs) with multiple stellar populations. All the formation scenarios predict that secondary population stars are enhanced in helium but the exact helium content depends on the…
We present an accurate analysis of the peculiar Horizontal Branch (HB) of the massive Galactic globular cluster NGC 2808, based on high-resolution far-UV and optical images of the central region of the cluster obtained with HST. We confirm…
Despite the efforts of the past decade, the origin of the bimodal horizontal-branch (HB) found in some globular clusters (GCs) remains a conundrum. Inspired by the discovery of multiple stellar populations in the {\it most massive} Galactic…
Some Ultra Diffuse Galaxies (UDGs) appear to host exceptionally rich globular cluster (GC) systems compared to normal galaxies of the same stellar mass. After re-examing these claims, we focus on a small sample of UDGs from the literature…
It is well known that metal-poor red giant branch (RGB) stars show variations in some elemental abundances, including carbon, due to the internal mixing accompanied by their own in situ CN cycle in the hydrogen burning shell. With our new…