scholarly journals Globular Cluster Systems: Comparison with the Milky Way

2002 ◽  
Vol 207 ◽  
pp. 68-72
Author(s):  
Dante Minniti
Keyword(s):  
Globular Cluster ◽  
Reference Point ◽  
Luminosity Function ◽  
Milky Way ◽  
Elliptical Galaxy ◽  
Cluster System ◽  
Cluster Systems ◽  
Distant Galaxies ◽  
Globular Cluster System

The Milky Way globular cluster system serves as a reference for the study of more distant galaxies. Here I stress that there are still things we do not know about the globular cluster system of our own galaxy: their total number, their spatial motions and distances, and their IR properties. If our best reference point is not fully known, caution should be exercised when interpreting observations of distant systems. At the same time, when studying distant ellipticals it is not always advisable to rely on the Milky Way as a comparison. For example, only recently the first full calibration of the luminosity function of the globular cluster system of an elliptical galaxy was made, necessary to compare apples with apples.

What do globular clusters tell us about isolated ellipticals? The case of NGC 6411

2019 ◽  
Vol 14 (S351) ◽  
pp. 60-63
Author(s):  
J. P. Caso ◽  
Lilia P. Bassino ◽  
T. Richtler ◽  
R. Salinas
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Luminosity Function ◽  
Elliptical Galaxy ◽  
Cluster System ◽  
Colour Distribution ◽  
Globular Cluster System

AbstractWe summarize the results from a study of the globular cluster (GC) system of the isolated elliptical galaxy NGC 6411, based on Gemini/GMOS g', r', i’ photometry. The extent of the globular cluster system is about 70 kpc. It contains ≍700 members. The colour distribution and luminosity function are typical of old GC systems. An excess of bright GCs with intermediate colours might evidence an intermediate-age merger.

scholarly journals An Overview of Globular Cluster Systems in Distant Galaxies

1988 ◽  
Vol 126 ◽  
pp. 237-253 ◽  
Author(s):  
William E. Harris
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Luminosity Function ◽  
Milky Way ◽  
Special Role ◽  
Spatial Structures ◽  
Coma Cluster ◽  
Cluster Systems ◽  
Distant Galaxies

Information is currently available for globular cluster systems in almost 50 galaxies from the Milky Way to the Coma Cluster. The observed features of these systems are reviewed, with emphasis on (a) their total populations (specific frequencies), (b) spatial structures compared with the underlying halo light, (c) photometric characteristics (luminosity function and metallicity). The combined evidence suggests strongly that globular clusters are likely to have formed in a rather sharply defined epoch clearly before the bulk of the halo field stars, and that this epoch was more active in E galaxies, especially those in rich environments. Finally, the special role of the supergiant E's at the centers of rich galaxy clusters is reviewed.

scholarly journals Metallicity Gradients in Globular Cluster Systems: the Trace of a Self-Enrichment Process?

2002 ◽  
Vol 207 ◽  
pp. 733-735
Author(s):  
G. Parmentier ◽  
P. Magain ◽  
A. Noels ◽  
A. Thoul ◽  
E. Jehin
Keyword(s):  
Globular Cluster ◽  
Common Property ◽  
First Generation ◽  
Galactic Halo ◽  
Cluster System ◽  
Type Ii ◽  
Cluster Systems ◽  
Globular Cluster System ◽  
Enrichment Process

We have developed a model of globular cluster self-enrichment, based on the ability of the globular cluster gaseous progenitors to retain the ejecta of a first generation of Type II Supernovae. The key point is that this ability depends on the pressure exerted on the progenitor cloud by the surrounding protogalactic medium and therefore on the location of the cloud in the protogalaxy. The model is able to explain the galactic halo metallicities and the metallicity gradient of the Old Halo which is thought to be the genuine galactic globular cluster system. The possibility that metallicity gradients are a common property of extragalactic globular cluster systems is also presented.

scholarly journals Deep Wide-Field Photometry of the NGC 5128 Globular Cluster System: A Progress Report

2002 ◽  
Vol 207 ◽  
pp. 309-311
Author(s):  
G. L. H. Harris ◽  
D. Geisler ◽  
W. E. Harris ◽  
J. E. Hesser
Keyword(s):  
Globular Cluster ◽  
Luminosity Function ◽  
Progress Report ◽  
Cluster System ◽  
Wide Field ◽  
Preliminary Results ◽  
System A ◽  
Globular Cluster System

We have obtained CMR photometry for a roughly 1° square region centered on NGC 5128. Preliminary results indicate that the limiting magnitude of the images is ≳ 1 magnitude fainter than the peak of the globular cluster luminosity function (GCLF) at R ⋍ 21.

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.

The Dynamics of Globular Cluster Systems

1988 ◽  
Vol 126 ◽  
pp. 641-642
Author(s):  
Natarajan Ramamani
Keyword(s):  
Gravitational Field ◽  
Globular Cluster ◽  
Cluster System ◽  
Spherically Symmetric ◽  
Cluster Systems ◽  
The Galaxy ◽  
Galaxy Model ◽  
Globular Cluster System ◽  
Hubble Time

This paper describes a project whose aim is to study the dynamics of a globular cluster system using an N-body code modified to include the gravitational field of an isothermal galaxy model. The galaxy and the globular cluster system have the same radii, are spherically symmetric and non-rotating. The evolution is to be followed up to a Hubble time.

Globular cluster system of NGC 3613, a massive elliptical galaxy in a poor environment

2019 ◽  
Vol 14 (S351) ◽  
pp. 84-88
Author(s):  
Bruno J. De Bórtoli ◽  
Lilia P. Bassino ◽  
Juan P. Caso ◽  
Ana I. Ennis
Keyword(s):  
Globular Cluster ◽  
Elliptical Galaxy ◽  
Cluster System ◽  
Host Galaxy ◽  
Low Density ◽  
Stellar Component ◽  
Magnitude Diagram ◽  
The Galaxy ◽  
Colour Distribution ◽  
Globular Cluster System

AbstractWe present an analysis of the globular cluster system (GCS) of the galaxy NGC 3613, an intrinsically bright elliptical galaxy (MV = −21.5) in a low density environment (it is the central galaxy of a group of a dozen galaxies). Based on Gemini/GMOS photometry of NGC 3613 we obtained the following properties for this GCS. A ‘blue tilt’ is detected in the colour-magnitude diagram. The colour distribution is bimodal, presenting the two classical globular cluster (GC) sub-populations. The spatial and azimuthal projected distributions show that red sub-population correlates with the stellar component of the host galaxy.

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