scholarly journals Analytical Binary Modeling and its Role in Dynamics

2006 ◽  
Vol 2 (S240) ◽  
pp. 650-651
Author(s):  
Tapan K. Chatterjee
Keyword(s):  
Globular Clusters ◽  
Mass Density ◽  
Cluster Formation ◽  
Galactic Dynamics ◽  
Dynamic Evolution ◽  
Kinetic Temperature ◽  
Stellar Systems ◽  
External Effects ◽  
Dynamical Properties ◽  
Internal Evolution

Binaries are critical tools that drive stellar systems; which play a major role in galactic dynamics. Internal evolution of globular clusters, e.g., due to evolution of binaries, can be modulated by external effects, like tidal shocks (e.g., Chernoff & Weinberg 1990). There are well-established relations between dynamical properties of globular clusters and their galactrocentric distance, R(g). A characteristic one is: D(1/2) ≈ [R(g)]1/2, where D(1/2) is the diameter containing half the mass / luminosity in projection (van den Bergh et al. 1991). This relation could be a result of tidal evaporation of clusters and feedback of forming protoclusters (Surdin, 1995). A similar limitation of globular cluster distributions is obtained in the half-mass density kinetic temperature plot and used in many cluster formation scenarios (Muray & Lin 1992). This relationship should have an explanation on the basis of dynamic evolution of the cluster population.

scholarly journals Neutron Stars in Globular Clusters

2007 ◽  
Vol 3 (S246) ◽  
pp. 316-320 ◽  
Author(s):  
N. Ivanova ◽  
C. O. Heinke ◽  
F. Rasio
Keyword(s):  
Neutron Stars ◽  
Numerical Simulations ◽  
Globular Clusters ◽  
Stellar Systems ◽  
Large Scatter ◽  
X Ray ◽  
Dynamical Properties ◽  
X Ray Binaries ◽  
Collision Number ◽  
Good Agreement

AbstractDynamical interactions that occur between objects in dense stellar systems are particularly important for the question of formation of X-ray binaries. We present results of numerical simulations of 70 globular clusters with different dynamical properties and a total stellar mass of 2×107M⊙. We find that in order to retain enough neutron stars to match observations we must assume that NSs can be formed via electron-capture supernovae. Our simulations explain the observed dependence of the number of LMXBs on “collision number” as well as the large scatter observed between different globular clusters. For millisecond pulsars, we obtain good agreement between our models and the numbers and characteristics of observed pulsars in the clusters Terzan 5 and 47 Tuc.

scholarly journals Effects of initial density profiles on massive star cluster formation in giant molecular clouds

2021 ◽  
Author(s):  
Yingtian Chen ◽  
Hui Li ◽  
Mark Vogelsberger
Keyword(s):  
Angular Momentum ◽  
Star Formation ◽  
Molecular Clouds ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Initial Density ◽  
Giant Molecular Clouds ◽  
Density Profiles ◽  
Stellar Feedback ◽  
Gas Accretion

Abstract We perform a suite of hydrodynamic simulations to investigate how initial density profiles of giant molecular clouds (GMCs) affect their subsequent evolution. We find that the star formation duration and integrated star formation efficiency of the whole clouds are not sensitive to the choice of different profiles but are mainly controlled by the interplay between gravitational collapse and stellar feedback. Despite this similarity, GMCs with different profiles show dramatically different modes of star formation. For shallower profiles, GMCs first fragment into many self-gravitation cores and form sub-clusters that distributed throughout the entire clouds. These sub-clusters are later assembled ‘hierarchically’ to central clusters. In contrast, for steeper profiles, a massive cluster is quickly formed at the center of the cloud and then gradually grows its mass via gas accretion. Consequently, central clusters that emerged from clouds with shallower profiles are less massive and show less rotation than those with the steeper profiles. This is because 1) a significant fraction of mass and angular momentum in shallower profiles is stored in the orbital motion of the sub-clusters that are not able to merge into the central clusters 2) frequent hierarchical mergers in the shallower profiles lead to further losses of mass and angular momentum via violent relaxation and tidal disruption. Encouragingly, the degree of cluster rotations in steeper profiles is consistent with recent observations of young and intermediate-age clusters. We speculate that rotating globular clusters are likely formed via an ‘accretion’ mode from centrally-concentrated clouds in the early Universe.

scholarly journals Uniting old stellar systems: from globular clusters to giant ellipticals

2008 ◽  
Vol 389 (4) ◽  
pp. 1924-1936 ◽  
Author(s):  
Duncan A. Forbes ◽  
Paul Lasky ◽  
Alister W. Graham ◽  
Lee Spitler
Keyword(s):  
Globular Clusters ◽  
Stellar Systems

scholarly journals Photometric Models for Globular Clusters from Population Synthesis

1988 ◽  
Vol 126 ◽  
pp. 559-560
Author(s):  
R. Capuzzo Dolcetta
Keyword(s):  
Structural Properties ◽  
Globular Clusters ◽  
Magellanic Cloud ◽  
Stellar Systems ◽  
Population Synthesis ◽  
Stellar Content ◽  
Cloud Clusters ◽  
Metal Abundance ◽  
Theoretical Frame

Integral fluxes (Bolometric and U, B, V) are computed in a completely theoretical frame in order to investigate the structural properties and stellar content of coeval stellar systems of various ages and metal abundance. Some results concerning the problem of the color gap in the distribution of the sample of Magellanic Cloud clusters are discussed.

scholarly journals The Ghosts of Galaxies: Tidal Debris in Clusters

2004 ◽  
Vol 217 ◽  
pp. 70-76
Author(s):  
Michael D. Gregg ◽  
Michael J. West
Keyword(s):  
Globular Clusters ◽  
Surface Brightness ◽  
Large Scale ◽  
Dwarf Galaxies ◽  
Cluster Formation ◽  
X Ray ◽  
Cluster Evolution ◽  
Low Surface Brightness ◽  
Intergalactic Space ◽  
Formation And Evolution

Gravitational interactions in rich clusters can strip material from the outer parts of galaxies or even completely disrupt entire systems, giving rise to large scale, low surface brightness ghostly features stretching across intergalactic space. The nearby Coma and Centaurus clusters both have striking examples of galaxy ghosts, in the form of 100 kpc-long plumes of intergalactic debris. By searching HST archival images, we have found numerous other examples of galaxy ghosts in rich clusters at low redshift, evidence that galaxy destruction and recycling are ubiquitous, important in cluster formation and evolution, and continue to mold clusters at the present epoch. Many ghosts appear in X-ray bright clusters, perhaps signaling a connection with energetic subcluster mergers.The fate of such material has important ramifications for cluster evolution. Our new HST WFPC2 V & I images of a portion of the Centaurus plume reveal that it contains an excess of discrete objects with −12 < MV < −6, consistent with being globular clusters or smaller dwarf galaxies. This tidally liberated material is being recycled directly into the intracluster population of stars, dwarf galaxies, globular clusters, and gas, which may have been built largely from a multitude of similar events over the life of the cluster.

scholarly journals Dynamical models of spheroidal multi-component stellar systems

2019 ◽  
Vol 14 (S351) ◽  
pp. 273-276
Author(s):  
Caterina Caravita ◽  
Luca Ciotti ◽  
Silvia Pellegrini
Keyword(s):  
Globular Clusters ◽  
Mass Function ◽  
Mass Scale ◽  
Initial Mass Function ◽  
Dark Matter Halo ◽  
Numerical Code ◽  
Stellar Systems ◽  
Rotating Disks ◽  
Structural Density ◽  
Systematic Effects

Abstract. We present a significantly improved version of our numerical code JASMINE, that can now solve the Jeans equations for axisymmetric models of stellar systems, composed of an arbitrary number of stellar populations, a Dark Matter halo, and a central Black Hole. The stellar components can have different structural (density profile, flattening, mass, scale length), dynamical (rotational support, velocity dispersion anisotropy), and population (age, metallicity, Initial Mass Function, mass-to-light ratio) properties. These models, when combined with observations, will allow to investigate important issues, such as quantifying the systematic effects of IMF variations, of mass-to-light ratio gradients, and of different stellar kinematic components (e.g. counter rotating disks, kinematically decoupled cores) on luminosity-weighted properties. The developed analytical and numerical framework aims at modeling Early-Type Galaxies, but it can also be applied to dwarf Spheroidal galaxies and Globular Clusters.

scholarly journals Dynamics of Globular Cluster Systems

1983 ◽  
Vol 100 ◽  
pp. 359-364
Author(s):  
K. C. Freeman
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Cluster Formation ◽  
Active Phase ◽  
Chemical Abundance ◽  
Cluster Systems ◽  
Chemical Enrichment ◽  
Wide Range ◽  
The Galaxy

In the Milky Way, the globular clusters are all very old, and we are accustomed to think of them as the oldest objects in the Galaxy. The clusters cover a wide range of chemical abundance, from near solar down to about [Fe/H] ⋍ −2.3. However there are field stars with abundances significantly lower than −2.3 (eg Bond, 1980); this implies that the clusters formed during the active phase of chemical enrichment, with cluster formation beginning at a time when the enrichment processes were already well under way.

scholarly journals Star Clusters in Irregular Galaxies in the Local Group

2002 ◽  
Vol 207 ◽  
pp. 94-104
Author(s):  
Eva K. Grebel
Keyword(s):  
Globular Clusters ◽  
Local Group ◽  
Cluster Formation ◽  
Star Clusters ◽  
Open Clusters ◽  
High Angular Resolution ◽  
Star Clusters And Associations ◽  
Star Forming ◽  
Star Forming Regions ◽  
Irregular Galaxies

I summarize our knowledge of star clusters and associations in irregular galaxies other than the Magellanic Clouds in the Local Group. Surveys affording complete area coverage at high angular resolution are still lacking. Confirmed globular clusters are known only in NGC 6822 and WLM. Very few dIrrs contain populous or sparse open clusters. There is a pronounced deficiency of intermediate-age and young clusters. Apart from parent galaxy mass, the lack of interactions may be a key reason for the lack of cluster formation in the dIrrs. All dIrrs have one or several short-lived OB associations in the star-forming regions in their centers.

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