Related papers: Blue Hook Stars in Globular Clusters
We characterize the population of blue horizontal-branch (BHB) stars in the bulge-halo transition region of the Milky Way using the VISTA Variables in the V\'ia L\'actea (VVV) ESO Public Survey data. The selection of BHB stars is made using…
Following a review of our present knowledge about blue subdwarf stars in globular clusters, we present an overview of the results of searches for close binaries among these stars, including results previously published in the literature and…
The growing population of binary black holes (BBHs) observed by gravitational wave detectors is a potential Rosetta stone for understanding their formation channels. Here, we use an upgraded version of our semi-analytic codes {\sc…
The recent observations of gravitational waves (GWs) by the LIGO-Virgo-KAGRA collaboration (LVK) have provided a new opportunity for studying our Universe. By detecting several merging events of black holes (BHs), LVK has spurred the…
With about a hundred mergers of binary black holes (BBHs) detected via gravitational waves by the LIGO-Virgo-KAGRA (LVK) Collaboration, our understanding of the darkest objects in the Universe has taken unparalleled steps forward. While…
Globular clusters could harbor massive central black holes (BHs), just as galaxies do. So far, no unambiguous detection of a massive BH has been reported for any globular cluster. However, the dense core-collapsed cluster M15 seems to be a…
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…
This paper explores if, and to what an extent, the stellar populations of early type galaxies can be traced through the colour distribution of their globular cluster systems. The analysis, based on a galaxy sample from the Virgo ACS data,…
We present preliminary results obtained from the comparison of the specific frequencies of Blue Straggler Stars (BSS) detected so far in a sample of 26 Galactic globular clusters. The number of BSS seems to increase almost linearly with…
The discovery of a large population of intra-cluster star clusters in the central region of the Hydra I and Centaurus galaxy clusters is presented. Based on deep VLT photometry (V,I), many star clusters have been identified not only around…
Enhancement and spread of helium among globular cluster stars have been recently suggested as a way to explain the horizontal branch blue tails, in those clusters which show a primordial spread in the abundances of CNO and other elements…
We study the long term dynamical evolution of stellar mass black holes (BHs) at the Galactic center (GC) and put constraints on their number and central mass distribution. Models of the GC are considered that have not yet achieved a steady…
Surveys with the Hubble Space Telescope find supermassive black holes (BHs) of 10**6 to 10**9.5 solar masses in every galaxy that has an elliptical-galaxy-like "bulge" component. BHs appear to be standard equipment in galaxy bulges. At the…
Previous spectroscopic analyses of Blue Horizontal Branch (BHB) stars in six globular clusters revealed too low masses in four clusters when compared to canonical evolutionary theory, while the masses of the BHB stars in NGC 6752 and M 5…
The distribution of stars around a massive black hole (MBH) has been addressed in stellar dynamics for the last four decades by a number of authors. Because of its proximity, the centre of the Milky Way is the only observational test case…
In a Globular Cluster (GC), the mass loss during the red-giant branch (RGB) phase and the helium content are fundamental ingredients to constrain the horizontal branch (HB) morphology. While many papers have been dedicated to the helium…
Blue horizontal-branch stars are Population II objects which are burning helium in their core and possess a hydrogen-burning shell and radiative envelope. Because of their low rotational velocities, diffusion has been predicted to work in…
After taking into account, for the first time, the detailed systematic variation of horizontal-branch (HB) morphology with age and metallicity, our population synthesis models show that the integrated H beta index is significantly affected…
Recent studies suggest that the helium content of multiple stellar populations in globular clusters (GCs) is not uniform. The range of helium varies from cluster to cluster with more massive GCs having, preferentially, large helium spread.…
A large fraction of galactic nuclei is expected to host supermassive black hole binaries (BHB), likely formed during the early phase of galaxies assembly and merging. In this paper, we use a large set of state-of-art numerical models to…