Related papers: Blue Stragglers as Stellar Collision Products: the…
Recent progress in the understanding of star formation is summarized. A consistent picture is emerging where molecular clouds form with turbulent velocity fields and clumpy substructure, imprinted already during their formation. The clouds…
The spin-down of Be stars due to angular momentum transport from star to disc has been considered. This has been prompted by empirical studies of observed optical and IR line profile studies indicating that the disc is rotating in a…
Blue lurkers (BLs) are rejuvenated main-sequence stars hidden among normal main-sequence stars on color-magnitude diagrams of star clusters. In comparison, the blue straggler stars, formed via similar mass transfers or mergers, occupy a…
We investigate the origin of the observed scaling $j\sim R^{3/2}$ between the specific angular momentum $j$ and the radius $R$ of molecular clouds (MCs) and their their substructures, and of the observed near independence of $\beta$, the…
We investigate the triggering of star formation and the formation of stellar clusters in molecular clouds that form as the ISM passes through spiral shocks. The spiral shock compresses gas into $\sim$100 pc long main star formation ridge,…
The blue straggler phenomenon is not yet well explained by current theory; however, evolutionary models of star clusters call for a good knowledge of it. Here we try to understand the possible formation scenario of HD 73666, a blue…
Recent Spitzer observations of the globular cluster M15 detected dust associated with its intracluster medium. Surprisingly, these observations imply that the dust must be very short-lived compared to the time since the last Galactic plane…
Magnetic activity is known to be correlated to the rotation period for moderately active main sequence solar-like stars. In turn, the stellar rotation period evolves as a result of magnetised stellar winds that carry away angular momentum.…
Astronomical observation of stellar rotation suggests that at least the surface layers of the Sun have lost a substantial amount of the angular momentum that they possessed at the beginning of the main-sequence phase of evolution; and…
We developed angular momentum evolution models for 0.5 and 0.8 $M_{\odot}$ stars. The parametric models include a new wind braking law based on recent numerical simulations of magnetised stellar winds, specific dynamo and mass-loss rate…
Dynamical friction due to field stars and tidal disruption caused by a central nucleus are crucial in determining the evolution of the globular cluster system in an elliptical galaxy. In this paper I examine the possibility that some of…
Circumstellar discs of Be stars are thought to be formed from material ejected from a fast-spinning central star. This material possesses large amounts of angular momentum and settles in a quasi-Keplerian orbit around the star. This simple…
Stars lose a significant amount of angular momentum between birth and death, implying that efficient processes transporting it from the core to the surface are active. Space asteroseismology delivered the interior rotation rates of more…
This chapter presents an overview of the main observational results obtained to date about Blue Straggler Stars (BSSs) in Galactic Globular Clusters (GCs). The BSS specific frequency, radial distribution, chemical composition and rotational…
The behaviour of the transverse momentum fluctuations with the centrality of the collision shown by the Relativistic Heavy Ion Collider data is naturally explained by the clustering of color sources. In this framework, elementary color…
High-resolution {\sl Hubble Space Telescope} imaging observations show that the radial distribution of the field-decontaminated sample of 162 'blue straggler' stars (BSs) in the $11.7^{+0.2}_{-0.1}$ Gyr-old Large Magellanic Cloud cluster…
Close encounters between neutron stars and main-sequence stars occur in globular clusters and may lead to various outcomes. Here we study encounters resulting in tidal disruption of the star. Using $N$-body models, we predict the typical…
We use hydrodynamic simulations of minor mergers of galaxies to investigate the nature of surface brightness excesses at large radii observed in some spiral galaxies: antitruncated stellar disks. We find that this process can produce the…
We study the dynamics of continuum driven winds from rotating stars, and develop an approximate analytical model. We then discuss the evolution of stellar angular momentum, and show that just above the Eddington limit, the winds are…
In the cores of young dense star clusters repeated stellar collisions involving the same object can occur, which has been suggested to lead to the formation of an intermediate-mass black hole. In order to verify this scenario we compute the…