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

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 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.

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.

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 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.

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