scholarly journals Evolution of the Galactic Globular Cluster System

1996 ◽  
Vol 174 ◽  
pp. 401-402
Author(s):  
E. Vesperini
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Initial Conditions ◽  
Structural Parameters ◽  
Mass Function ◽  
Cluster System ◽  
The Galaxy ◽  
Globular Cluster System ◽  
Individual Cluster

Recent surveys of the observational properties of galactic globular clusters have shown the existence of interesting correlations and trends between structural parameters and between structural parameters and location inside the Galaxy (Chernoff & Djorgovski 1989, Djorgovski & Meylan 1994). The origin of most of these correlations is not clear yet and it is not clear to what extent they reflect the primordial conditions or the result of evolution. We have carried out a set of simulations following the evolution of the properties of a globular cluster system (mass function, spatial distribution, correlations between structural parameters) starting from given initial conditions. The evolution of each individual cluster has been followed by the same method applied by Chernoff et al. (1986) and Chernoff & Shapiro (1987). The effects of internal relaxation, disk shocking and dynamical friction have been considered. The main goal of the analysis is that of establishing the role of initial conditions and evolutionary processes in determining the present observational properties.

scholarly journals An Overview of the Globular Cluster System of the Galaxy

1988 ◽  
Vol 126 ◽  
pp. 37-48
Author(s):  
Robert Zinn
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Galactic Center ◽  
Galactic Plane ◽  
Cluster System ◽  
Open Clusters ◽  
The Galaxy ◽  
Globular Cluster System ◽  
Harlow Shapley

Harlow Shapley (1918) used the positions of globular clusters in space to determine the dimensions of our Galaxy. His conclusion that the Sun does not lie near the center of the Galaxy is widely recognized as one of the most important astronomical discoveries of this century. Nearly as important, but much less publicized, was his realization that, unlike stars, open clusters, HII regions and planetary nebulae, globular clusters are not concentrated near the plane of the Milky Way. His data showed that the globular clusters are distributed over very large distances from the galactic plane and the galactic center. Ever since this discovery that the Galaxy has a vast halo containing globular clusters, it has been clear that these clusters are key objects for probing the evolution of the Galaxy. Later work, which showed that globular clusters are very old and, on average, very metal poor, underscored their importance. In the spirit of this research, which started with Shapley's, this review discusses the characteristics of the globular cluster system that have the most bearing on the evolution of the Galaxy.

scholarly journals Observational Constraints on the Formation and Evolution of Globular Cluster Systems

2007 ◽  
Vol 3 (S246) ◽  
pp. 394-402
Author(s):  
Stephen E. Zepf
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Dynamical Evolution ◽  
Mass Function ◽  
Cluster System ◽  
Host Galaxy ◽  
Cluster Systems ◽  
Cluster Mass ◽  
Formation And Evolution ◽  
Globular Cluster System

AbstractThis paper reviews some of the observational properties of globular cluster systems, with a particular focus on those that constrain and inform models of the formation and dynamical evolution of globular cluster systems. I first discuss the observational determination of the globular cluster luminosity and mass function. I show results from new very deep HST data on the M87 globular cluster system, and discuss how these constrain models of evaporation and the dynamical evolution of globular clusters. The second subject of this review is the question of how to account for the observed constancy of the globular cluster mass function with distance from the center of the host galaxy. The problem is that a radial trend is expected for isotropic cluster orbits, and while the orbits are observed to be roughly isotropic, no radial trend in the globular cluster system is observed. I review three extant proposals to account for this, and discuss observations and calculations that might determine which of these is most correct. The final subject is the origin of the very weak mass-radius relation observed for globular clusters. I discuss how this strongly constrains how globular clusters form and evolve. I also note that the only viable current proposal to account for the observed weak mass-radius relation naturally effects the globular cluster mass function, and that these two problems may be closely related.

scholarly journals The Globular Cluster System of NGC 5128: Ages, Metallicities, Kinematics and Structural Parameters

2010 ◽  
Vol 27 (4) ◽  
pp. 379-389 ◽  
Author(s):  
K. A. Woodley ◽  
M. Gómez
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Structural Parameters ◽  
Cluster System ◽  
High Signal ◽  
Galactocentric Distance ◽  
Noise Spectroscopy ◽  
Formation And Evolution ◽  
Globular Cluster System ◽  
Cluster Age

AbstractWe review our recent studies of the globular cluster system of NGC 5128. First, we have obtained low-resolution, high signal-to-noise spectroscopy of 72 globular clusters using Gemini-S/GMOS to obtain the ages, metallicities, and the level of alpha enrichment of the metal-poor and metal-rich globular cluster subpopulations. Second, we have explored the rotational signature and velocity dispersion of the galaxy's halo using over 560 globular clusters with radial velocity measurements. We have also compared the dependence of these properties on galactocentric distance and globular cluster age and metallicity. Using globular clusters as tracer objects, we have analyzed the mass, and mass-to-light ratio of NGC 5128. Last, we have measured the structural parameters, such as half-light radii, of over 570 globular clusters from a superb 1.2-square-degree Magellan/IMACS image. We will present the findings of these studies and discuss the connection to the formation and evolution of NGC 5128.

scholarly journals Mass and shape of the Milky Way’s dark matter halo with globular clusters from Gaia and Hubble

2019 ◽  
Vol 621 ◽  
pp. A56 ◽  
Author(s):  
Lorenzo Posti ◽  
Amina Helmi
Keyword(s):  
Dark Matter ◽  
Phase Space ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Cluster System ◽  
Dark Matter Halo ◽  
Proper Motions ◽  
Axis Ratio ◽  
The Galaxy ◽  
Globular Cluster System

Aims. We estimate the mass of the inner (< 20 kpc) Milky Way and the axis ratio of its inner dark matter halo using globular clusters as tracers. At the same time, we constrain the distribution in phase-space of the globular cluster system around the Galaxy. Methods. We use the Gaia Data Release 2 catalogue of 75 globular clusters’ proper motions and recent measurements of the proper motions of another 20 distant clusters obtained with the Hubble Space Telescope. We describe the globular cluster system with a distribution function (DF) with two components: a flat, rotating disc-like one and a rounder, more extended halo-like one. While fixing the Milky Way’s disc and bulge, we let the mass and shape of the dark matter halo and we fit these two parameters, together with six others describing the DF, with a Bayesian method. Results. We find the mass of the Galaxy within 20 kpc to be M(<20 kpc) = 1.91−0.17+0.18×1011 M⊙, of which MDM(<20 kpc) = 1.37−0.17+0.18×1011 M⊙ is in dark matter, and the density axis ratio of the dark matter halo to be q = 1.30 ± 0.25. Assuming a concentration-mass relation, this implies a virial mass Mvir = 1.3±0.3×1012 M⊙. Our analysis rules out oblate (q <  0.8) and strongly prolate halos (q >  1.9) with 99% probability. Our preferred model reproduces well the observed phase-space distribution of globular clusters and has a disc component that closely resembles that of the Galactic thick disc. The halo component follows a power-law density profile ρ ∝ r−3.3, has a mean rotational velocity of Vrot ≃ −14km s−1 at 20 kpc, and has a mildly radially biased velocity distribution (β ≃ 0.2 ± 0.07, which varies significantly with radius only within the inner 15 kpc). We also find that our distinction between disc and halo clusters resembles, although not fully, the observed distinction in metal-rich ([Fe/H] > −0.8) and metal-poor ([Fe/H] ≤ −0.8) cluster populations.

scholarly journals Dynamical Evolution of the Mass Function of the Globular Cluster System from Fokker-Planck Calculations: Preliminary Results

2006 ◽  
Vol 2 (S235) ◽  
pp. 110-110
Author(s):  
Jihye Shin ◽  
Sungsoo S. Kim
Keyword(s):  
Stellar Evolution ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Dynamical Evolution ◽  
Mass Function ◽  
Cluster System ◽  
Dynamical Friction ◽  
Luminosity Functions ◽  
Globular Cluster System ◽  
Fokker Planck

AbstractUsing anisotropic Fokker-Planck models, we calculate the evolution of mass and luminosity functions of the Galactic globular cluster system. Our models include two-body relaxation, binary heating, tidal shocks, dynamical friction, and stellar evolution. We perform Fokker-Planck simulations for a large number of virtual globular clusters and synthesize these results to study the relation between the initial and present GCMFs.

scholarly journals Dynamical Evolution of the Mass Function of the Galactic Globular Cluster System

2007 ◽  
Vol 3 (S246) ◽  
pp. 433-434
Author(s):  
Jihye Shin ◽  
Sungsoo S. Kim ◽  
Koji Takahashi
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Dynamical Evolution ◽  
Mass Function ◽  
Cluster System ◽  
Peak Mass ◽  
Low Mass ◽  
Globular Cluster System ◽  
Log Normal ◽  
Mass Functions

AbstractUsing the most advanced anisotropic (2D) Fokker-Planck (FP) models, we calculate the evolution of the mass functions of the Galactic globular cluster system (GCMF). Our models include two-body relaxation, binary heating, tidal shocks, dynamical friction, stellar evolution, and realistic cluster orbits. We perform 2D-FP simulations for a large number of virtual globular clusters and synthesize these results to study the relation between the initial and present GCMFs. We found two probable IGCMFs that eventually evolve into the Milky Way GCMF : truncated power-law, and log-normal model with higher initial low mass limit and peak mass than the earlier studies.

scholarly journals The Globular Cluster System of the Galaxy NGC 6876

Galaxies ◽  
2017 ◽  
Vol 5 (3) ◽  
pp. 30 ◽  
Author(s):  
Ana Ennis ◽  
Lilia Bassino ◽  
Juan Caso
Keyword(s):  
Globular Cluster ◽  
Cluster System ◽  
The Galaxy ◽  
Globular Cluster System

scholarly journals Metallicity maps of the globular cluster system in the Galaxy

1993 ◽  
Vol 402 ◽  
pp. L53 ◽  
Author(s):  
Emilio J. Alfaro ◽  
Jesus Cabrera-Cano ◽  
Antonio J. Delgado
Keyword(s):  
Globular Cluster ◽  
Cluster System ◽  
The Galaxy ◽  
Globular Cluster System

Globular cluster tidal interactions and mergers in the Galactic disc

2019 ◽  
Vol 14 (S351) ◽  
pp. 442-446
Author(s):  
Alessandra Mastrobuono-Battisti ◽  
Sergey Khoperskov ◽  
Paola Di Matteo ◽  
Misha Haywood
Keyword(s):  
Globular Cluster ◽  
Iron Content ◽  
Globular Clusters ◽  
Dynamical Evolution ◽  
Stellar Populations ◽  
Cluster System ◽  
Galactic Disc ◽  
Tidal Interactions ◽  
Globular Cluster System ◽  
Shed Light

AbstractThe Galactic globular cluster system went and is still going through dynamical processes that require to be explored in detail. Here we illustrate how primordial massive globular clusters born in the Milky Way’s disc evolved by stripping material from each other or even merging very early during their lives. These processes might explain the puzzling presence of star-by-star spreads in iron content observed in massive globular clusters and should be taken into account when studying globular cluster stellar populations. In this context, we show how the direct comparison between the predictions provided by our direct N-body simulations and observations can shed light on the origin and chemo-dynamical evolution of globular clusters.

Sign in / Sign up

Export Citation Format

Share Document