The eye of Gaia on globular cluster kinematics: Internal rotation

2019 ◽  
Vol 14 (S351) ◽  
pp. 516-519
Author(s):  
A. Sollima ◽  
H. Baumgardt ◽  
M. Hilker
Keyword(s):  
Internal Rotation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Stellar Systems ◽  
Large Sample ◽  
Data Release ◽  
Extensive Collection ◽  
Formation And Evolution ◽  
The Impact ◽  
Insight Into

AbstractI present the results of a survey of the kinematics of a large sample of Galactic globular clusters performed thanks to the synergy between the 2nd Gaia data release and the most extensive collection of radial velocities. This unprecedented dataset of 3D velocities of thousand of stars in 62 globular clusters has been used to investigate the rotation patterns of these stellar systems providing insight into the impact of two-body relaxation and tides on the formation and evolution of their rotation.

scholarly journals Rotation and Flattening of Globular Clusters

1985 ◽  
Vol 113 ◽  
pp. 285-296 ◽  
Author(s):  
S. Michael Fall ◽  
Carlos S. Frenk
Keyword(s):  
Angular Momentum ◽  
Internal Rotation ◽  
Globular Clusters ◽  
Pressure Support ◽  
Initial Conditions ◽  
Anisotropic Pressure ◽  
Stellar Systems ◽  
Galactic Globular Clusters

Pease and Shapley (1917) first remarked on the apparent flattening of several Galactic globular clusters, a view that has been confirmed by many subsequent studies. Tidal stresses, internal rotation, and velocity anisotropies can cause deviations from sphericity in stellar systems. In general, we might expect globular clusters to have some angular momentum at the time of formation and, if they collapsed from flattened initial conditions, to have anisotropic pressure support. Since the velocity distributions within the clusters can be altered by a variety of internal and external processes, their shapes are expected to evolve. In this article, we review the methods for measuring ellipticities and the results that have emerged from such studies. Our main purpose, however, is to discuss the processes that determine the shapes of globular clusters and the ways in which they change with time.

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.

Internal kinematics of multiple stellar populations in globular clusters

2019 ◽  
Vol 14 (S351) ◽  
pp. 324-328
Author(s):  
Mattia Libralato
Keyword(s):  
High Precision ◽  
Globular Clusters ◽  
Hubble Space Telescope ◽  
Stellar Populations ◽  
Stellar Systems ◽  
Proper Motions ◽  
Space Telescope ◽  
Formation And Evolution ◽  
Galactic Globular Clusters ◽  
Shed Light

AbstractSpectroscopy and photometry have revealed existence, complexity and properties of the multiple stellar populations (mPOPs) hosted in Galactic globular clusters. However, the conundrum of the formation and evolution of mPOPs is far from being completely exploited: the available pieces of information seem not enough to shed light on these topics. Astrometry, and in particular high-precision proper motions, can provide us the sought-after answers about how mPOPs formed and have evolved in these ancient stellar systems. In the following, I present a brief overview of the observational results on the internal kinematics of the mPOPs in some GCs thanks to Hubble Space Telescope high-precision proper motions.

scholarly journals Theoretical Implications of the 47 Tuc Pulsars

2000 ◽  
Vol 177 ◽  
pp. 589-594
Author(s):  
Frederic A. Rasio
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Radio Pulsars ◽  
Formation And Evolution ◽  
Millisecond Radio

AbstractTwenty millisecond radio pulsars have now been observed in the globular cluster 47 Tuc. This is by far the largest sample of radio pulsars known in any globular cluster. These recent observations provide a unique opportunity to re-examine theoretically the formation and evolution of recycled pulsars in globular clusters.

scholarly journals Erratum: Binary black hole mergers from globular clusters: the impact of globular cluster properties

2019 ◽  
Vol 491 (4) ◽  
pp. 5793-5793
Author(s):  
Jongsuk Hong ◽  
Enrico Vesperini ◽  
Abbas Askar ◽  
Mirek Giersz ◽  
Magdalena Szkudlarek ◽  
...  
Keyword(s):  
Black Hole ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Binary Black Hole ◽  
Cluster Properties ◽  
The Impact

scholarly journals A new era for the globular cluster system in M31

2009 ◽  
Vol 5 (S266) ◽  
pp. 117-122
Author(s):  
Myung Gyoon Lee ◽  
Sang Chul Kim ◽  
Ho Seong Hwang ◽  
Hong Soo Park ◽  
Doug Geisler ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
Cluster System ◽  
Entire Body ◽  
Wide Field ◽  
Chemical Abundance ◽  
New Era ◽  
Group A ◽  
Formation And Evolution ◽  
Globular Cluster System

AbstractThe globular cluster system in M31 is an ideal laboratory for studying the formation and evolution of M31 as well as the globular clusters themselves. There have been numerous surveys and studies of the globular clusters in M31. However, only recently has the entire body of M31 been searched for globular clusters using wide-field CCD images by our group. A new era for the M31 globular cluster system has begun with the advent of wide-field CCD surveys of M31. We have discovered more than 100 new globular clusters in M31. Our catalog currently includes more than 500 globular clusters confirmed either based on spectra or HST images, many more than in the Milky Way. We present the structure, kinematics and chemical abundance of the M31 globular cluster system based on this large sample, and the implications for the formation and evolution of M31.

scholarly journals The Formation and Evolution of Star Clusters and Galaxies

2005 ◽  
Vol 13 ◽  
pp. 347-349
Author(s):  
Stephen E. Zepf
Keyword(s):  
Galaxy Formation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Near Infrared ◽  
Cluster Formation ◽  
Star Clusters ◽  
Elliptical Galaxies ◽  
Cluster Systems ◽  
Important Observation ◽  
Formation And Evolution

AbstractThis paper addresses the questions of what we have learned about how and when dense star clusters form, and what studies of star clusters have revealed about galaxy formation and evolution. One important observation is that globular clusters are observed to form in galaxy mergers and starbursts in the local universe, which both provides constraints on models of globular cluster formation, and suggests that similar physical conditions existed when most early-type galaxies and their globular clusters formed in the past. A second important observation is that globular cluster systems typically have bimodal color distributions. This was predicted by merger models, and indicates an episodic formation history for elliptical galaxies. A third and very recent result is the discovery of large populations of intermediate age globular clusters in several elliptical galaxies through the use of optical to near-infrared colors. These provide an important link between young cluster systems observed in starbursts and mergers and old cluster systems. This continuum of ages of the metal-rich globular cluster systems also indicates that there is no special age or epoch for the formation of the metal-rich globular clusters, which comprise about half of the cluster population. The paper concludes with a brief discussion of recent results on the globular cluster – low-mass X-ray binary connection.

scholarly journals Extragalactic Globular Cluster Systems in the Near-IR

2002 ◽  
Vol 207 ◽  
pp. 294-300 ◽  
Author(s):  
Thomas H. Puzia ◽  
Markus Kissler-Patig ◽  
Jean Brodie ◽  
Paul Goudfrooij ◽  
Michael Hilker ◽  
...  
Keyword(s):  
Galaxy Formation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Local Group ◽  
Optical Photometry ◽  
Cluster Systems ◽  
Near Ir ◽  
Galaxy Formation And Evolution ◽  
First Results ◽  
Formation And Evolution

Extragalactic Globular Clusters are useful tracers of galaxy formation and evolution. Photometric studies of globular cluster systems beyond the Local Group are still the most popular method to investigate their physical properties, such as their ages and metallicities. However, the limitations of optical photometry are well known. The better wavelength sampling of the underlying cluster's SED using K-band photometry combined with optical passbands allows us to create colors which reduce the age-metallicity degeneracy to the largest extent. Here we report on the very first results of our near-IR photometric survey of globular cluster systems in early-type galaxies outside the Local Group.

scholarly journals Globular Clusters as Probes of the Formation History of Elliptical Galaxies: Results for NGC 4472

2002 ◽  
Vol 207 ◽  
pp. 333-335
Author(s):  
K.L. Rhode ◽  
S.E. Zepf
Keyword(s):  
Galaxy Formation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Spiral Galaxies ◽  
Elliptical Galaxy ◽  
Elliptical Galaxies ◽  
Cluster Systems ◽  
Large Sample ◽  
Formation History ◽  
History Of

We have undertaken a survey of the globular cluster systems of a large sample of elliptical and spiral galaxies in order to test predictions of elliptical galaxy formation models. Here we outline the survey and present a summary of our results for the Virgo elliptical NGC 4472.

scholarly journals Discovery of rotation axis alignments in Milky Way globular clusters

2020 ◽  
Vol 638 ◽  
pp. L12
Author(s):  
Andrés E. Piatti
Keyword(s):  
Gravitational Field ◽  
Internal Rotation ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Milky Way ◽  
Rotation Axis ◽  
Relaxation Times ◽  
Orbit Inclination ◽  
Inclination Angles ◽  
Rotation Strength

There is an increasing number of recent observational results that show that some globular clusters exhibit internal rotation while they travel along their orbital trajectories around the Milky Way center. Based on these findings, we searched for any relationship between the inclination angles of the globular cluster orbits with respect to the Milky Way plane and those of their rotation. We discovered that the relative inclination, in the sense of inclination of the rotation axis to orbit axis, is a function of the orbit inclination of the globular cluster. Rotation and orbit axes are aligned for an inclination of ∼56°, while the rotation axis inclination is far from the orbit inclination between ∼20° and −20° when the latter increases from 0° up to 90°. We further investigated the origin of this linear relationship and found no correlation with the semimajor axes and eccentricities of the globular cluster orbits, nor with the internal rotation strength, the globular cluster sizes, actual and tidally disrupted masses, or half-mass relaxation times, among others. The uncovered relationship will affect the development of numerical simulations of the internal rotation of globular clusters, our understanding of the interaction of globular clusters with the gravitational field of the Milky Way, and the observational campaigns made to increase the number of globular clusters with detected internal rotation.

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