Related papers: Constraining white-dwarf kicks in globular cluster…
Globular clusters can form inside their host galaxies at high redshift when gas densities were higher and gas-rich mergers were common. They can also form inside lower-mass galaxies that have since been accreted and tidally disrupted,…
It is well known that the energy input from massive stars dominates the thermal and mechanical heating of typical regions in the interstellar medium of galaxies. These effects are amplified tremendously in the immediate environment of young…
Massive stars in young massive clusters insert tremendous amounts of mass and energy into their surroundings in the form of stellar winds and supernova ejecta. Mutual shock-shock collisions lead to formation of hot gas, filling the volume…
Multiple stellar populations are observed in almost all globular-clusters, but the origin of this phenomenon is still debated. We investigate the role cool supergiants may have played. To do this, we combine two investigative methods:…
Globular clusters are often assumed to be good tracers of major star formation episodes in their host galaxies. While observations over the past 2 decades have confirmed the presence of young objects with globular cluster-like properties in…
Recent work on globular cluster systems in dwarf galaxies outside the Local Group is reviewed. Recent large imaging surveys with the Hubble Space Telescope and follow-up spectroscopy with 8-m class telescopes now allow us to compare the…
We estimate the number of individual, fast-moving stars observable in globular clusters under the assumption that the clusters contain massive central black holes which follow the galactic black-hole mass vs. sigma relationship. We find…
Star cluster formation is a major mode of star formation in the extreme conditions of interacting galaxies and violent starbursts. Young clusters are observed to form in a variety of such galaxies, a substantial number resembling the…
Mergers of massive gas-rich galaxies trigger violent starbursts that - over timescales of $> 100$ Myr and regions $> 10$ kpc - form massive and compact star clusters comparable in mass and radii to Galactic globular clusters. The star…
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,…
We consider the early cooling evolution of strongly magnetized strange stars in a CFL phase with high gap Delta > 100 MeV. We demonstrate how this model may explain main features of the gamma-ray burst phenomena and also yield a strong star…
Most stars form in compact, dense embedded clusters with memberships ranging from a dozen stars to many millions of stars. Embedded clusters containing more than a few hundred stars also contain O stars that disrupt the nebula abruptly.…
The evolution of globular cluster systems in some galaxies can be cause of merging of globulars in the very central regions. This high stellar density favours the growth of a central nucleus via swallowing of surrounding stars. The infall…
Little is known about the origins of the giant star clusters known as globular clusters. How can hundreds of thousands of stars form simultaneously in a volume only a few light years across the distance of the sun to its nearest neighbor?…
The existence of supermassive black holes lurking in the centers of galaxies and of stellar binary systems containing a black hole with a few solar masses has been established beyond reasonable doubt. The idea that black holes of…
In dense stellar systems the frequent dynamical interactions between stars play a crucial role in the formation and evolution of compact binaries. We study these processes using a novel approach combining a state-of-the-art binary…
Utilizing a series of N-body simulations, we argue that gravitationally bound stellar clusters of modest population evolve very differently from the picture presented by classical dynamical relaxation theory. The system's most massive stars…
The orbital decay and tidal disruption of a star cluster in a galaxy is studied in an analytical manner. Owing to dynamical friction, the star cluster spirals in toward the center of the galaxy. Simultaneously, the galactic tidal field…
Observations show the presence, in the halo of our Galaxy, of stars moving at velocities so high to require an acceleration mechanism involving the presence of a massive central black hole. Thus, in the frame of a galaxy hosting a…
Circumstellar disks of planetary debris are now known or suspected to closely orbit hundreds of white dwarf stars. To date, both data and theory support disks that are entirely contained within the preceding giant stellar radii, and hence…