Deep Luminosity Functions of Old and Intermediate-Age Globular Clusters in NGC 1316: Evidence for Dynamical Evolution of Second-Generation Globular Clusters

AbstractI summarize the scenario by Goudfrooij (2018) in which the bulk of the ultraviolet (UV) upturn of giant early-type galaxies (ETGs) is due to helium-rich stellar populations that formed in massive metal-rich globular clusters (GCs) and subsequently dissolved in the strong tidal field in the central regions of the massive host galaxy. These massive GCs are assumed to show UV upturns similar to those observed recently in M87, the central galaxy in the Virgo cluster of galaxies. Data taken from the literature reveals a strong correlation between the strength of the UV upturn and the specific frequency of metal-rich GCs in ETGs. Adopting a Schechter function parametrization of GC mass functions, simulations of long-term dynamical evolution of GC systems show that this correlation can be explained by variations in the characteristic truncation mass Mc such that Mc increases with ETG luminosity in a way that is consistent with observed GC luminosity functions in ETGs. These findings suggest that the nature of the UV upturn in ETGs and the variation of its strength among ETGs are causally related to that of helium-rich populations in massive GCs, rather than intrinsic properties of field stars in ETGs.

Download Full-text

Massive stars in globular clusters: drivers of chemical and dynamical evolution

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311010465 ◽

2010 ◽

Vol 6 (S272) ◽

pp. 227-232

Author(s):

Thibault Decressin

Keyword(s):

Globular Cluster ◽

Globular Clusters ◽

Second Generation ◽

Massive Stars ◽

Dynamical Evolution ◽

Strong Impact ◽

Low Velocity ◽

Cluster Evolution ◽

The One ◽

Mechanical Mass

AbstractMassive stars have a strong impact on globular cluster evolution. First providing they rotate initially fast enough they can reach the break-up velocity during the main sequence and a mechanical mass-loss will eject matter from the equator at low velocity. Rotation-induced mixing will also bring matter from the convective core to the surface. From this ejected matter loaded in H-burning material a second generation of stars will born. The chemical pattern of these second generation stars are similar to the one observed for stars in globular cluster with abundance anomalies in light elements. Then during the explosion as supernovae the massive stars will also clear the cluster of the remaining gas. If this gas expulsion process acts on short timescale it can strongly modify the dynamical properties of clusters by ejecting preferentially first generation stars.

Download Full-text

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

Proceedings of the International Astronomical Union ◽

10.1017/s1743921306005424 ◽

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.

Download Full-text

Evolution of Globular Clusters Formed in Mergers

Symposium - International Astronomical Union ◽

10.1017/s0074180900224467 ◽

2002 ◽

Vol 207 ◽

pp. 630-641

Author(s):

François Schweizer

Keyword(s):

Globular Clusters ◽

First Generation ◽

Second Generation ◽

Pressure Increase ◽

Giant Molecular Clouds ◽

Simultaneous Formation ◽

Luminosity Functions ◽

Solar Metallicity ◽

S0 Galaxies ◽

Rapid Pressure

Globular clusters formed in galactic mergers (e.g., The Antennae) can now be studied at different stages of their evolution. In young merger remnants (e.g., NGC 7252) these “second-generation” globulars appear by the hundreds as young halo clusters of roughly solar metallicity. While at first bluer and much more luminous than old metal-poor globulars, they become redder after 1–1.5 Gyr and can then be observed as still overluminous red clusters of intermediate age in perturbed-looking E and S0 galaxies (e.g., NGC 1316, 1700, 3610). There is evidence from the color distributions, projected radial distributions, and perhaps also luminosity functions that these clusters eventually assume the properties of red metal-rich globulars observed in many giant ellipticals. Studies of globular clusters in ongoing mergers and young remnants suggest that second-generation globulars form from giant molecular clouds shocked by the rapid pressure increase in the merger-induced starburst. This pressure-induced formation lends credence to Cen's (2001) argument that the general pressure increase during cosmological reionization at z ≈ 7–15 triggered the near-simultaneous formation of the universal population of first-generation metal-poor globulars observed in galaxies of all types.

Download Full-text

The ages of Galactic globular clusters in the context of self-enrichment

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309031913 ◽

2008 ◽

Vol 4 (S258) ◽

pp. 265-274 ◽

Cited By ~ 3

Author(s):

T. Decressin ◽

H. Baumgardt ◽

P. Kroupa ◽

G. Meynet ◽

C. Charbonnel

Keyword(s):

Globular Clusters ◽

First Generation ◽

Second Generation ◽

Age Determination ◽

Dynamical Evolution ◽

Low Velocity ◽

Tidal Forces ◽

History Of ◽

First And Second Generation

AbstractA significant fraction of stars in globular clusters (about 70%-85%) exhibit peculiar chemical patterns, with strong abundance variations in light elements along with constant abundances in heavy elements. These abundance anomalies can be created in the H-burning core of a first generation of fast-rotating massive stars, and the corresponding elements are conveyed to the stellar surface thanks to rotational induced mixing. If the rotation of the stars is fast enough, this material is ejected at low velocity through a mechanical wind at the equator. It then pollutes the interstellar medium (ISM) from which a second generation of chemically anomalous stars can be formed. The proportion of anomalous stars to normal stars observed today depends on at least two quantities: (1) the number of polluter stars; (2) the dynamical history of the cluster, which may lose different proportions of first- and second-generation stars during its lifetime. Here we estimate these proportions, based on dynamical models for globular clusters. When internal dynamical evolution and dissolution due to tidal forces are accounted for, starting from an initial fraction of anomalous stars of 10% produces a present-day fraction of about 25%, still too small with respect to the observed 70-85%. In the case of gas expulsion by supernovae, a much higher fraction is expected to be produced. In this paper we also address the question of the evolution of the second-generation stars that are He-rich, and deduce consequences for the age determination of globular clusters.

Download Full-text

Luminosity Functions for Globular Clusters

The Astrophysical Journal ◽

10.1086/306483 ◽

1998 ◽

Vol 509 (1) ◽

pp. 192-202 ◽

Cited By ~ 17

Author(s):

Fabio Silvestri ◽

Paolo Ventura ◽

Francesca D'Antona ◽

Italo Mazzitelli

Keyword(s):

Globular Clusters ◽

Luminosity Functions

Download Full-text

Dynamical evolution of multiple-population globular clusters

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab223 ◽

2021 ◽

Vol 502 (3) ◽

pp. 4290-4304

Author(s):

Enrico Vesperini ◽

Jongsuk Hong ◽

Mirek Giersz ◽

Arkadiusz Hypki

Keyword(s):

Structural Properties ◽

Globular Clusters ◽

First Generation ◽

Radial Profile ◽

Dynamical Evolution ◽

Evolutionary Phase ◽

Dynamical Parameters ◽

Energy Equipartition

ABSTRACT We have carried out a set of Monte Carlo simulations to study a number of fundamental aspects of the dynamical evolution of multiple stellar populations in globular clusters with different initial masses, fractions of second generation (2G) stars, and structural properties. Our simulations explore and elucidate: (1) the role of early and long-term dynamical processes and stellar escape in the evolution of the fraction of 2G stars and the link between the evolution of the fraction of 2G stars and various dynamical parameters; (2) the link between the fraction of 2G stars inside the cluster and in the population of escaping stars during a cluster’s dynamical evolution; (3) the dynamics of the spatial mixing of the first-generation (1G) and 2G stars and the details of the structural properties of the two populations as they evolve toward mixing; (4) the implications of the initial differences between the spatial distribution of 1G and 2G stars for the evolution of the anisotropy in the velocity distribution and the expected radial profile of the 1G and 2G anisotropy for clusters at different stages of their dynamical history; and (5) the variation of the degree of energy equipartition of the 1G and the 2G populations as a function of the distance from the cluster’s centre and the cluster’s evolutionary phase.

Download Full-text

Contribution of White Dwarfs to Cluster Masses

Highlights of Astronomy ◽

10.1017/s1539299600021651 ◽

1998 ◽

Vol 11 (1) ◽

pp. 430-432

Author(s):

Ted Von Hippel

Keyword(s):

Stellar Evolution ◽

Mass Fraction ◽

Globular Clusters ◽

White Dwarfs ◽

Literature Search ◽

Galactic Disk ◽

Dynamical Evolution ◽

Open Clusters ◽

Solar Neighborhood ◽

Current Evidence

The study of cluster white dwarfs (WDs) has been invigorated recently bythe Hubble Space Telescope (HST). Recent WD studies have been motivated by the new and independent cluster distance (Renzini et al. 1996), age (von Hippel et al. 1995; Richer et al. 1997), and stellar evolution (Koester & Reimers 1996) information that cluster WDs can provide. An important byproduct of these studies has been an estimate of the WD mass contribution in open and globular clusters. The cluster WD mass fraction is of importance for understanding the dynamical state and history of star clusters. It also bears an important connection to the WD mass fractions of the Galactic disk and halo. Current evidence indicates that the open clusters (e.g. von Hippel et al. 1996; Reid this volume) have essentially the same luminosity function (LF) as the solar neighborhood population. The case for the halo is less clear, despite the number of very good globular cluster LFs down to nearly 0.1 solar masses (e.g. Cool et al. 1996; Piotto, this volume), as the field halo LF is poorly known. For most clusters dynamical evolution should cause evaporation of the lowest mass members, biasing clusters to have flatter present-day mass functions (PDMFs) than the disk and halo field populations. Dynamical evolution should also allow cluster WDs to escape, though not in the same numbers as the much lower mass main sequence stars. The detailed connection between cluster PDMFs and the field IMF awaits elucidation from observations and the new combined N-body and stellar evolution models (Tout, this volume). Nevertheless, the WD mass fraction of clusters already provides an estimate for the WD mass fraction of the disk and halo field populations. A literature search to collect cluster WDs and a simple interpretive model follow. This is a work in progress and the full details of the literature search and the model will be published elsewhere.

Download Full-text

Dynamical Evolution of Globular Clusters After Core Collapse

Symposium - International Astronomical Union ◽

10.1017/s0074180900147357 ◽

1985 ◽

Vol 113 ◽

pp. 139-160 ◽

Cited By ~ 4

Author(s):

Douglas C. Heggie

Keyword(s):

Surface Density ◽

Globular Clusters ◽

Stellar System ◽

Dynamical Evolution ◽

Theoretical Models ◽

Numerical Calculations ◽

Core Collapse ◽

Density Profiles ◽

The Core ◽

Fokker Planck

This review describes work on the evolution of a stellar system during the phase which starts at the end of core collapse. It begins with an account of the models of Hénon, Goodman, and Inagaki and Lynden-Bell, as well as evaporative models, and modifications to these models which are needed in the core. Next, these models are related to more detailed numerical calculations of gaseous models, Fokker-Planck models, N-body calculations, etc., and some problems for further work in these directions are outlined. The review concludes with a discussion of the relation between theoretical models and observations of the surface density profiles and statistics of actual globular clusters.

Download Full-text

Dynamical Evolution of Globular Clusters with Mass Spectrum

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000024838 ◽

1991 ◽

Vol 9 (1) ◽

pp. 41-44

Author(s):

Hyung Mok Lee

Keyword(s):

Mass Spectrum ◽

Globular Clusters ◽

Numerical Models ◽

Relaxation Times ◽

Dynamical Evolution ◽

Planck Equation ◽

Mass Function ◽

Low Mass Stars ◽

Wide Range ◽

Three Body

AbstractWe present a series of numerical models describing the dynamical evolution of globular clusters with a mass spectrum, based on integration of the Fokker-Planck equation. We include three-body binary heating and a steady galactic tidal field. A wide range of initial mass functions is adopted and the evolution of the mass function is examined. The mass function begins to change appreciably during the post-collapse expansion phase due to the selective evaporation of low mass stars through the tidal boundary. One signature of highly evolved clusters is thus the significant flattening of the mass function. The age (in units of the half-mass relaxation time) increases very rapidly beyond about 100 signifying the final stage of cluster disruption. This appears to be consistent with the sharp cut-off of half-mass relaxation times at near 108 years for the Galactic globular clusters.

Download Full-text