scholarly journals Formation of Twin Clusters in a Galactic Tidal Field

2002 ◽  
Vol 207 ◽  
pp. 681-683
Author(s):  
Christian Theis
Keyword(s):  
Globular Clusters ◽  
Unsolved Problem ◽  
Cluster Formation ◽  
Equal Mass ◽  
Star Cluster ◽  
Stellar Clusters ◽  
Galactocentric Distance ◽  
Galactic Potential ◽  
Self Gravity ◽  
Single Cluster

The formation of globular clusters is still an unsolved problem. Though most scenarios assume a massive molecular cloud as the progenitor, it is unclear how the cloud is transformed into a star cluster. Here a scheme of supernova (SN) induced cluster formation is investigated. In this scenario the expanding SN shell accumulates the mass of the cloud. This is accompanied by fragmentation resulting in star formation in the shell. If this stellar shell expands sufficiently slowly, its self-gravity leads to a recollapsing shell, thus forming one or several stellar clusters.In this paper N-body simulations of collapsing shells moving on circular orbits in a galactic potential are presented. It is shown that typical shells (105 M⊙, 30 pc) evolve to twin clusters in the galactocentric distance range between 3 and 11 kpc. Their masses show a strong radial trend: on orbits inside 5 kpc both clusters have almost equal mass. Outside 5 kpc the more massive twin cluster contains about 55% of the shell's mass, whereas the mass of the smaller decreases linearily to 15% at 11 kpc. Outside 11 kpc the collapsing shells end up in a single cluster. Inside 3 kpc the shells are tidally disrupted and only fragments substantially less massive than the initial shell survive.

scholarly journals Star cluster dynamics

2010 ◽  
Vol 368 (1913) ◽  
pp. 829-849 ◽  
Author(s):  
Enrico Vesperini
Keyword(s):  
Globular Clusters ◽  
Cluster Formation ◽  
Cluster Structure ◽  
Dynamical Evolution ◽  
Star Cluster ◽  
Stellar Content ◽  
Cluster Systems ◽  
Detailed Understanding ◽  
Term Evolution

Dynamical evolution plays a key role in shaping the current properties of star clusters and star cluster systems. A detailed understanding of the effects of evolutionary processes is essential to be able to disentangle the properties that result from dynamical evolution from those imprinted at the time of cluster formation. In this review, I focus my attention on globular clusters, and review the main physical ingredients driving their early and long-term evolution, describe the possible evolutionary routes and show how cluster structure and stellar content are affected by dynamical evolution.

scholarly journals On the initial mass-radius relation of stellar clusters

2021 ◽  
Author(s):  
Nick Choksi ◽  
J M Diederik Kruijssen
Keyword(s):  
High Pressure ◽  
Globular Clusters ◽  
High Redshift ◽  
Cluster Formation ◽  
Stellar Clusters ◽  
Population Synthesis ◽  
Star Forming ◽  
Massive Clusters ◽  
Good Agreement ◽  
Environmental Dependence

Abstract Young stellar clusters across nearly five orders of magnitude in mass appear to follow a power-law mass-radius relationship (MRR), $R_{\star }\propto M_{\star }^{\alpha }$, with α ≈ 0.2 − 0.33. We develop a simple analytic model for the cluster mass-radius relation. We consider a galaxy disc in hydrostatic equilibrium, which hosts a population of molecular clouds that fragment into clumps undergoing cluster formation and feedback-driven expansion. The model predicts a mass-radius relation of $R_{\star }\propto M_{\star }^{1/2}$ and a dependence on the kpc-scale gas surface density $R_{\star }\propto \Sigma _{\rm g}^{-1/2}$, which results from the formation of more compact clouds (and cluster-forming clumps within) at higher gas surface densities. This environmental dependence implies that the high-pressure environments in which the most massive clusters can form also induce the formation of clusters with the smallest radii, thereby shallowing the observed MRR at high-masses towards the observed $R_{\star }\propto M_{\star }^{1/3}$. At low cluster masses, relaxation-driven expansion induces a similar shallowing of the MRR. We combine our predicted MRR with a simple population synthesis model and apply it to a variety of star-forming environments, finding good agreement. Our model predicts that the high-pressure formation environments of globular clusters at high redshift naturally led to the formation of clusters that are considerably more compact than those in the local Universe, thereby increasing their resilience to tidal shock-driven disruption and contributing to their survival until the present day.

scholarly journals Galactic flows and the formation of stellar clusters

2015 ◽  
Vol 12 (S316) ◽  
pp. 184-189
Author(s):  
Romas Smilgys ◽  
Ian A. Bonnell
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Cluster Formation ◽  
Stellar Clusters ◽  
Gravitational Instabilities ◽  
Merging Process ◽  
Original Region ◽  
Sph Simulation ◽  
Self Gravity ◽  
Massive Clusters

AbstractWe investigate the formation of stellar clusters from a Galactic scale SPH simulation. The simulation traces star formation over a 5.6 Myr timescale, with local gravitational instabilities resulting in ~ 105 solar masses of star formation in the form of sink particles. We investigate the time evolution of the physical properties of the forming clusters including their half-mass radii, their energies and the depletion time of the gas. Star formation is driven by the large scale flows which compress the gas to higher densities where self gravity takes over and collapse occurs. We show that the more massive clusters (up to ~ 2 × 104 solar masses) gather their material from of order 10 pc due to these large scale motions associated with the spiral arm passage and shock. The bulk of the gas becomes gravitationally bound near 1-2 Myr before sink formation, and in the absence of feedback, significant accretion ongoing on longer timescales. We trace the hierarchical merging process of cluster formation which naturally results in age spreads of order the crossing time of the original region which provides the gas reservoir for the cluster.

scholarly journals Massive star cluster formation and evolution in tidal dwarf galaxies

2019 ◽  
Vol 628 ◽  
pp. A60 ◽  
Author(s):  
Jérémy Fensch ◽  
Pierre-Alain Duc ◽  
Médéric Boquien ◽  
Debra M. Elmegreen ◽  
Bruce G. Elmegreen ◽  
...  
Keyword(s):  
Globular Clusters ◽  
Massive Star ◽  
Dwarf Galaxies ◽  
Cluster Formation ◽  
Spectral Energy Distribution ◽  
Star Clusters ◽  
Star Cluster ◽  
Spectral Energy ◽  
Physical Parameters ◽  
Near Ultraviolet

Context. The formation of globular clusters remains an open debate. Dwarf starburst galaxies are efficient at forming young massive clusters with similar masses as globular clusters and may hold the key to understanding their formation. Aims. We study star cluster formation in a tidal debris, including the vicinity of three tidal dwarf galaxies, in a massive gas-dominated collisional ring around NGC 5291. These dwarfs have physical parameters that differ significantly from local starbursting dwarfs. They are gas rich, highly turbulent, their gas metallicity is already enriched up to half solar values, and they are expected to be free of dark matter. The aim is to study massive star cluster formation in this as yet unexplored type of environment. Methods. We used imaging from the Hubble Space Telescope using broadband filters that cover the wavelength range from the near-ultraviolet to the near-infrared. We determined the masses and ages of the cluster candidates by using the spectral energy distribution-fitting code CIGALE. We considered age-extinction degeneracy effects on the estimation of the physical parameters. Results. We find that the tidal dwarf galaxies in the ring of NGC 5291 are forming star clusters with an average efficiency of ∼40%, which is similar to blue compact dwarf galaxies. We also find massive star clusters for which the photometry suggests that they were formed at the very birth of the tidal dwarf galaxies. These clusters have survived for several hundred million years. Therefore our study shows that extended tidal dwarf galaxies and compact clusters may be formed simultaneously. In the specific case observed here, the young star clusters are not massive enough to survive for a Hubble time. However, it may be speculated that similar objects at higher redshift, with a higher star formation rate, might form some of the long-lived globular clusters.

scholarly journals Low-luminosity Galaxies in the Early Universe Have Observed Sizes Similar to Star Cluster Complexes

2021 ◽  
Vol 162 (6) ◽  
pp. 255
Author(s):  
R. J. Bouwens ◽  
G. D. Illingworth ◽  
P. G. van Dokkum ◽  
B. Ribeiro ◽  
P. A. Oesch ◽  
...  
Keyword(s):  
Globular Cluster ◽  
Globular Clusters ◽  
High Redshift ◽  
Cluster Formation ◽  
Star Cluster ◽  
Single Star ◽  
Cluster Complexes ◽  
Star Forming ◽  
Comparison Sample ◽  
Upper Limits

Abstract We compare the sizes and luminosities of faint z = 6–8 galaxies magnified by the Hubble Frontier Fields clusters with star-forming regions, as well as more evolved objects, in the nearby universe. Our high-redshift comparison sample includes 330 z = 6–8 galaxies, for which size measurements were made as part of a companion study where lensing magnifications were estimated from various public models. Accurate size measurements for these sources are complicated by the lens model uncertainties, but other results and arguments suggest that faint galaxies are small, as discussed in a companion study. The measured sizes for sources in our comparison sample range from <50 pc to ∼500 pc. For many of the lowest-luminosity sources, extremely small sizes are inferred, reaching individual sizes as small as 10–30 pc, with several sources in the 10–15 pc range with our conservative magnification limits. The sizes and luminosities are similar to those of single star cluster complexes like 30 Doradus in the lower-redshift universe and—in a few cases—super star clusters. The identification of these compact, faint star-forming sources in the z ∼ 6–8 universe also allows us to set upper limits on the proto-globular cluster luminosity function at z ∼ 6. By comparisons of the counts and sizes with recent models, we rule out (with some caveats) proto-globular cluster formation scenarios favoring substantial (ξ = 10) post-formation mass loss and set useful upper limits on others. Our size results suggest we may be very close to discovering a bona fide population of forming globular clusters at high redshift.

scholarly journals The physics and modes of star cluster formation: observations

2010 ◽  
Vol 368 (1913) ◽  
pp. 713-731 ◽  
Author(s):  
Charles J. Lada
Keyword(s):  
Present State ◽  
Molecular Clouds ◽  
Cluster Formation ◽  
Star Cluster ◽  
Stellar Clusters ◽  
Empirical Knowledge ◽  
Physical Processes ◽  
Subsequent Evolution ◽  
Cluster Systems ◽  
Infrared Wavelengths

Stellar clusters are born in cold and dusty molecular clouds and the youngest clusters are embedded to various degrees in a dusty dark molecular material. Such embedded clusters can be considered protocluster systems. The most deeply buried examples are so heavily obscured by dust that they are only visible at infrared wavelengths. These embedded protoclusters constitute the nearest laboratories for a direct astronomical investigation of the physical processes of cluster formation and early evolution. I review the present state of empirical knowledge concerning embedded-cluster systems and discuss the implications for understanding their formation and subsequent evolution to produce bound stellar clusters.

Young massive clusters in Arp 299

2019 ◽  
Vol 14 (S351) ◽  
pp. 143-146
Author(s):  
Zara Randriamanakoto ◽  
Petri Väisänen
Keyword(s):  
Star Formation ◽  
Globular Clusters ◽  
Cluster Formation ◽  
Age Distribution ◽  
Star Cluster ◽  
Luminous Infrared Galaxies ◽  
Star Formation Activity ◽  
Formation And Evolution ◽  
Using Data ◽  
Formation Efficiency

AbstractBecause of their young ages and compact densities, young massive star clusters (YMCs) are widely considered as potential proto-globular clusters. They are ubiquitous in environments with ongoing star formation activity such as interacting luminous infrared galaxies. To determine the galactic environmental effects on the star cluster formation and evolution, we study the YMC population of Arp 299 (NGC 3690E/NGC 3690W) using data taken with the HST WFC3/UVIS camera. By fitting the multiband photometry with the Yggdrasil models, we derive the star cluster masses, ages and extinction. While the cluster mass-galactocentric radius relation of NGC 3690E indicates that there could be an influence of the gas density distribution on the cluster formation, the age distribution of the western component suggests that YMCs in that galaxy endure stronger disruption mechanisms. With a cluster formation efficiency of 19 percent, star formation happening in bound clusters in Arp 299 is 3–5 times higher than that of a typical normal spiral.

scholarly journals Linking globular cluster formation at low and high redshift through the age–metallicity relation in E-MOSAICS

2020 ◽  
Vol 500 (4) ◽  
pp. 4768-4778
Author(s):  
Danny Horta ◽  
Meghan E Hughes ◽  
Joel L Pfeffer ◽  
Nate Bastian ◽  
J M Diederik Kruijssen ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Mechanism ◽  
Globular Clusters ◽  
High Redshift ◽  
Cluster Formation ◽  
Star Cluster ◽  
Host Galaxies ◽  
Massive Galaxies ◽  
Low Metallicity ◽  
Massive Clusters

ABSTRACT We set out to compare the age–metallicity relation (AMR) of massive clusters from Magellanic Cloud mass galaxies in the E-MOSAICS suite of numerical cosmological simulations with an amalgamation of observational data of massive clusters in the Large and Small Magellanic Clouds (LMC/SMC). We aim to test if: (i) star cluster formation proceeds according to universal physical processes, suggestive of a common formation mechanism for young-massive clusters (YMCs), intermediate-age clusters (IACs), and ancient globular clusters (GCs); (ii) massive clusters of all ages trace a continuous AMR; and (iii) the AMRs of smaller mass galaxies show a shallower relation when compared to more massive galaxies. Our results show that, within the uncertainties, the predicted AMRs of L/SMC-mass galaxies with similar star formation histories to the L/SMC follow the same relation as observations. We also find that the metallicity at which the AMR saturates increases with galaxy mass, which is also found for the field star AMRs. This suggests that relatively low-metallicity clusters can still form in dwarfs galaxies. Given our results, we suggest that ancient GCs share their formation mechanism with IACs and YMCs, in which GCs are the result of a universal process of star cluster formation during the early episodes of star formation in their host galaxies.

scholarly journals Multiple stellar populations in massive LMC star clusters

2008 ◽  
Vol 4 (S256) ◽  
pp. 305-310
Author(s):  
A. D. Mackey ◽  
P. Broby Nielsen ◽  
A. M. N. Ferguson ◽  
J. C. Richardson
Keyword(s):  
Globular Clusters ◽  
Main Sequence ◽  
Cluster Formation ◽  
Star Clusters ◽  
Stellar Populations ◽  
Star Cluster ◽  
Magellanic Clouds ◽  
Formation And Evolution ◽  
Galactic Globular Clusters

AbstractThe recent discovery of multiple stellar populations in massive Galactic globular clusters poses a serious challenge for models of star cluster formation and evolution. A new angle on this problem is being provided by rich intermediate-age clusters in the Magellanic Clouds. In this contribution we describe the discovery of three such LMC clusters with peculiar main-sequence turn-off morphologies. The simplest interpretation of our observations is that each of these three clusters is comprised of two or more stellar populations spanning an age interval of ~300 Myr. Surprisingly, such features may not be unusual in this type of cluster.

scholarly journals On the Origin of Complex Stellar Populations in Star Clusters

2007 ◽  
Vol 3 (S246) ◽  
pp. 71-72
Author(s):  
J. Pflamm-Altenburg ◽  
P. Kroupa
Keyword(s):  
Star Formation ◽  
Globular Clusters ◽  
Massive Star ◽  
Cluster Formation ◽  
Star Clusters ◽  
Stellar Populations ◽  
Star Cluster ◽  
Young Stars

AbstractThe existence of complex stellar populations in some star clusters challenges the understanding of star formation. E.g. the ONC or the sigma Orionis cluster host much older stars than the main bulk of the young stars. Massive star clusters (ω Cen, G1, M54) show metallicity spreads corresponding to different stellar populations with large age gaps. We show that (i) during star cluster formation field stars can be captured and (ii) very massive globular clusters can accrete gas from a long-term embedding inter stellar medium and restart star formation.

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