Related papers: Horizontal Branch A- and B-type Stars in Globular …
We report the first results of an ongoing spectroscopic survey of blue horizontal branch stars in the metal-rich ([Fe/H] ~ -0.5) globular clusters NGC 6388 and NGC 6441. Based on data obtained with the ESO-New Technology Telescope (NTT), we…
In the first part of this article, we review observations of the mass and luminosity functions of young and old star cluster systems. We also review some of the physical processes that may determine the characteristic mass of globular…
Blue stragglers in globular clusters are abnormally massive stars that should have evolved off the stellar main sequence long ago. There are two known processes that can create these objects: direct stellar collisions and binary evolution.…
In this contribution I will discuss fundamental stellar parameters as determined from young star clusters; specifically those with ages less than or approximately equal to that of the Pleiades. I will focus primarily on the use of stellar…
We made a detailed analysis of the sample of 39 cluster spiral galaxies of various types observed at H$\alpha$ wavelength by Amram et al. (1992 to 1996), with a scanning Fabry-Perot. We plotted the outer gradient of their rotation curves as…
The dynamical evolution of the globular cluster systems in galaxies is predicted, based on the standard dynamical theory normalized to the example of the Milky Way. The major processes varying with the galactocentric distance are the tidal…
The theoretical discription of a hot star interior is obtained. It explains the distribution of stars over their masses, mass-radius-temperature and mass-luminosity dependencies. The theory of the apsidal rotation of binary stars and the…
Winds from massive stars have velocities of 1000 km/s or more, and produce hot, high pressure gas when they shock. We develop a theory for the evolution of bubbles driven by the collective winds from star clusters early in their lifetimes,…
The discovery of multiple stellar populations in globular clusters has implications for all the aspects of the study of these stellar systems. In this paper, by means of N-body simulations, we study the evolution of binary stars in…
The relics of building blocks that made stellar halo and bulge are yet to be discovered unless they were completely disrupted throughout the history of the Galaxy. Here we suggest that about 25% of the Milky Way globular clusters have…
Black holes (BHs) play a major role in the structural and dynamical evolutions of Globular Clusters (GCs). Several recent works searched for BHs in Galactic GCs using scaling relations derived from numerical simulations. However, the…
We investigate the properties of globular clusters in a galaxy cluster, using the particle tagging method with a semi-analytical approach in a cosmological context. We assume globular clusters form from dark matter halo mergers and their…
I present multiband optical and UV Hubble Space Telescope photometry of the two Galactic globular clusters NGC6388 and NGC6441, in order to investigate the nature of the physical mechanism(s) responsible for the existence of an extended…
The new generation of 3D hydrodynamical model atmospheres have been employed to study the impact of a realistic treatment of stellar convection on element abundance determinations of globular cluster stars for a range of atomic and…
Models based on their binary origin have been very successful in reproducing the properties of field subdwarf-B stars, but the observations of their analogues in globular clusters has posed new problems, while the discovery of multiple…
Globular clusters (GCs) are known to host multiple stellar populations showing chemical anomalies in the content of light elements. The origin of such anomalies observed in Galactic GCs is still debated. Here we analyse data compiled from…
Integrated spectroscopy is the method of choice for deriving the ages of unresolved stellar systems. However, hot stellar evolutionary stages, such as hot horizontal branch stars and blue straggler stars (BSSs), can affect the integrated…
In this paper we report on a curious feature in the V, (U-B) color-magnitude diagrams of globular clusters. In our database, we find that a considerable fraction of blue horizontal branch stars, hotter than the instability strip and cooler…
We present new evolutionary stellar models suitable for old Population I clusters, discussing both the consequences of the most recent improvements in the input physics and the effect of element diffusion within the stellar structures.…
We present our recent revision of model constructions for the horizontal-branch (HB) morphology of globular clusters, which suggests the HB morphology is more sensitive to age compared to our earlier models. We also present our high…