scholarly journals Internal secular evolution in disk galaxies: the growth of pseudobulges

2007 ◽  
Vol 3 (S245) ◽  
pp. 107-112 ◽  
Author(s):  
John Kormendy
Keyword(s):  
Galaxy Formation ◽  
Stellar Evolution ◽  
Globular Clusters ◽  
Protoplanetary Disks ◽  
Disk Galaxies ◽  
Core Collapse ◽  
Red Giants ◽  
Hot Jupiters ◽  
Secular Evolution ◽  
Theoretical Evidence

AbstractObservational and theoretical evidence that internal, slow (“secular”) evolution reshapes galaxy disks is reviewed in Kormendy & Kennicutt (2004). This update has three aims. First, I emphasize that this evolution is very general – it is as fundamental to the evolution of galaxy disks as (e. g.) core collapse is to globular clusters, as the production of hot Jupiters is to the evolution of protoplanetary disks, and as evolution to red giants containing proto-white-dwarfs is to stellar evolution. One consequence for disk galaxies is the buildup of dense central components that get mistaken for classical (i. e., merger-built) bulges but that were grown out of disk stars and gas. We call these pseudobulges. Second, I review new results on pseudobulge star formation and structure and on the distinction between boxy and disky pseudobulges. Finally, I highlight how these results make a galaxy formation problem more acute. How can hierarchical clustering produce so many pure disk galaxies with no evidence for merger-built bulges?

scholarly journals Hubble Space Telescope Studies of the Dense Central Regions of Globular Clusters

1996 ◽  
Vol 174 ◽  
pp. 19-28
Author(s):  
Puragra Guhathakurta ◽  
Brian Yanny ◽  
Donald P. Schneider ◽  
John N. Bahcall
Keyword(s):  
Density Profile ◽  
Globular Clusters ◽  
Hubble Space Telescope ◽  
Stellar Populations ◽  
Core Collapse ◽  
Red Giants ◽  
Space Telescope ◽  
Blue Straggler ◽  
Central Regions ◽  
Stellar Density

We present results from an ongoing program to probe the dense central parts of Galactic globular clusters using multicolor Hubble Space Telescope images (WF/PC-I and WFPC2). Our sample includes the dense clusters M15, 47 Tuc, M30, NGC 6624, M3 and M13. The two main goals of our program are to measure the shape of stellar density profile in clusters (the slope of the density cusp in post core collapse clusters, in particular) and to understand the nature of evolved stellar populations in very dense regions and their variation as a function of radius. The latter includes studies of blue straggler stars and of the central depletion of bright red giants. Our recent WFPC2 study of M15 is described in detail.

scholarly journals Magellanic globulars as cosmological tools

1991 ◽  
Vol 148 ◽  
pp. 165-169
Author(s):  
Alvio Renzini
Keyword(s):  
Galaxy Formation ◽  
Stellar Evolution ◽  
Globular Clusters ◽  
Star Clusters ◽  
Dynamical Evolution ◽  
Mass Range ◽  
Magellanic Clouds ◽  
Evolution Theory ◽  
Mass Functions ◽  
The Ideal

The globular clusters (GC) of the Magellanic Clouds play a very important role for many astrophysical and cosmological topics. For example, they represent the ideal testground for stellar evolution theory, they allow us to study the the early dynamical evolution of star clusters, to obtain accurate initial mass functions in a fairly extended mass range, to calibrate the Cepheid period-luminosity relation, and so on. In this brief paper I will touch upon two items which are of considerable cosmological interest, and about which Magellanic Cloud globulars provide unique information. These topics concern i) GC formation in galaxies, and ii) the epoch of galaxy formation.

scholarly journals The Effects of Stellar Evolution and Galactic Tides on Globular Cluster Evolution

1988 ◽  
Vol 126 ◽  
pp. 673-674
Author(s):  
D. F. Chernoff ◽  
M. D. Weinberg ◽  
S. L. Shapiro
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Core Collapse ◽  
Cluster Evolution

We investigate the evolution of globular clusters in the Galactic tidal field prior to core collapse. These multimass models incorporate mass loss by stellar evolution.

The core collapse of globular clusters with stellar evolution

1992 ◽  
Vol 196 (2) ◽  
pp. 191-198
Author(s):  
Chang-Hwan Kim ◽  
Mun-Suk Chun ◽  
Kyoung W. Min
Keyword(s):  
Stellar Evolution ◽  
Globular Clusters ◽  
Core Collapse ◽  
The Core

scholarly journals Evolution of Globular Clusters by Tidally-Captured Binaries through Core Collapse

1988 ◽  
Vol 126 ◽  
pp. 667-668
Author(s):  
Thomas S. Statler ◽  
Jeremiah P. Ostriker ◽  
Haldan N. Cohn
Keyword(s):  
Cross Sections ◽  
Stellar Evolution ◽  
Globular Clusters ◽  
Component Model ◽  
Core Collapse ◽  
Initial State ◽  
One Dimensional ◽  
Cluster Evolution ◽  
Two Component ◽  
Stellar Mergers

We present calculations of globular cluster evolution performed by a modified Fokker-Planck approach, in which binaries formed by tidal capture are followed explicitly, along with subsequent heating mechanisms. The cluster is simulated by a two component model, using the cross sections of Press and Teukolsky (1977) for tidal capture, those of Hut (1984) for the single-binary encounters and for distant binary-binary encounters, and those of Mikkola (1983) for the strong binary-binary encounters. The initial state of the cluster is a Plummer model with N = 3 × 105 and scale radius ro = 1.13 pc. All stars are identical, with mass M∗ = 0.7M⊙ and R∗ = 0.57R⊙. This gives an initial core radius rc = 0.8 pc, and one-dimensional dispersion σ = 11.6 km s-1. All binaries are assumed to be identical, with separation a = 2.5R∗. There are no binaries in the cluster initially. Additional important effects, such as tidal truncation, tidal shocks, stellar evolution and mass loss, and stellar mergers, are not included.

scholarly journals Extragalactic globular clusters: unraveling galaxy formation and constraining stellar evolution theories

2006 ◽  
Vol 2 (S241) ◽  
Author(s):  
A. Javier Cenarro ◽  
Michael A. Beasley ◽  
Jay Strader ◽  
Jean P. Brodie ◽  
Duncan A. Forbes
Keyword(s):  
Galaxy Formation ◽  
Stellar Evolution ◽  
Globular Clusters

scholarly journals Joint Discussion 8: Stellar Evolution in Real Time, Part IV Miscellany

1998 ◽  
Vol 11 (1) ◽  
pp. 377-377
Keyword(s):  
Real Time ◽  
Stellar Evolution ◽  
Main Theme ◽  
Secular Evolution ◽  
Time Part

For a number of interesting contributed papers at the JD8 it was not obvious at the meeting or later that their contents and conclusions are germane to the main theme of secular evolution evidences. The editors have decided that these papers should be listed by title only. They appear below in alphabetized order by (first or only) author.

scholarly journals Contribution of White Dwarfs to Cluster Masses

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.

scholarly journals Dynamical Evolution of Globular Clusters After Core Collapse

1985 ◽  
Vol 113 ◽  
pp. 139-160 ◽  
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.

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