scholarly journals Is there a fundamental upper limit to the mass of a star cluster?

2019 ◽  
Vol 488 (4) ◽  
pp. 5400-5408 ◽  
Author(s):  
Mark A Norris ◽  
Glenn van de Ven ◽  
Sheila J Kannappan ◽  
Eva Schinnerer ◽  
Ryan Leaman
Keyword(s):  
Cluster Formation ◽  
Star Clusters ◽  
Stellar Mass ◽  
Star Cluster ◽  
High Mass ◽  
Mass Star ◽  
Exact Nature ◽  
Turn Of The Millennium ◽  
Stellar Masses ◽  
Mass Dependent

Abstract The discovery around the turn of the millennium of a population of very massive (M⋆ > 2 × 106 M⊙) compact stellar systems (CSS) with physical properties (radius, velocity dispersion, stellar mass etc.) that are intermediate between those of the classical globular cluster (GC) population and galaxies led to questions about their exact nature. Recently a consensus has emerged that these objects, usually called ultracompact dwarfs (UCDs), are a mass-dependent mixture of high-mass star clusters and remnant nuclei of tidally disrupted galaxies. The existence of genuine star clusters with stellar masses >107 M⊙ naturally leads to questions about the upper mass limit of the star cluster formation process. In this work we compile a comprehensive catalogue of CSS, and reinforce the evidence that the true ancient star cluster population has a maximum mass of M⋆ ∼ 5 × 107 M⊙, corresponding to a stellar mass at birth of close to 108 M⊙. We then discuss several physical and statistical mechanisms potentially responsible for creating this limiting mass.

scholarly journals Cluster formation induced by a cloud–cloud collision in [DBS2003]179

2020 ◽  
Author(s):  
Sho Kuwahara ◽  
Kazufumi Torii ◽  
Norikazu Mizuno ◽  
Shinji Fujita ◽  
Mikito Kohno ◽  
...  
Keyword(s):  
Near Infrared ◽  
Cluster Formation ◽  
Dust Emission ◽  
Star Clusters ◽  
High Ratio ◽  
Star Cluster ◽  
High Mass ◽  
Mass Star ◽  
The Galaxy ◽  
Super Star Clusters

Abstract [DBS2003]179 is a super star cluster in the Galaxy discovered in deep near-infrared observations. We carried out CO $J$ = 1–0 and $J$ = 3–2 observations of the region of [DBS2003]179 with NANTEN2, ASTE, and the Mopra 22 m telescope. We identified and mapped two molecular clouds that are likely to be associated with the cluster. This association is supported by the spatial correlation with the corresponding 8$\, \mu$m Spitzer image and by a high ratio of the two transitions of $^{12}$CO($J$ = 3–2 and $J$ = 1–0). The two clouds show complementary distributions in space, and bridging features connect them in velocity. We hypothesize that the two clouds collided with each other 1–2 Myr ago and that the collision compressed the interfacial layer, triggering the formation of the cluster. This offers an additional piece of evidence for a super star cluster formed by a cloud–cloud collision, alongside the four super star clusters Westerlund$\:2$, NGC 3603, RCW 38, and R 136. These findings indicate that the known super star clusters with closely associated dust emission were formed by cloud–cloud collisions, lending support to the important role of cloud–cloud collisions in high-mass star formation.

scholarly journals RCW 36 in the Vela Molecular Ridge: Evidence for high-mass star-cluster formation triggered by cloud–cloud collision

2018 ◽  
Vol 70 (SP2) ◽  
Author(s):  
Hidetoshi Sano ◽  
Rei Enokiya ◽  
Katsuhiro Hayashi ◽  
Mitsuyoshi Yamagishi ◽  
Shun Saeki ◽  
...  
Keyword(s):  
Cluster Formation ◽  
Star Cluster ◽  
High Mass ◽  
Mass Star

scholarly journals Shock-induced star cluster formation in colliding galaxies

2010 ◽  
Vol 6 (S270) ◽  
pp. 483-486 ◽  
Author(s):  
Takayuki R. Saitoh ◽  
Hiroshi Daisaka ◽  
Eiichiro Kokubo ◽  
Junichiro Makino ◽  
Takashi Okamoto ◽  
...  
Keyword(s):  
High Resolution ◽  
Shock Compression ◽  
Smoothed Particle Hydrodynamics ◽  
Formation Process ◽  
Cluster Formation ◽  
Star Clusters ◽  
Star Cluster ◽  
Particle Hydrodynamics ◽  
Smoothed Particle ◽  
Number Of Particles

AbstractWe studied the formation process of star clusters using high-resolutionN-body/smoothed particle hydrodynamics simulations of colliding galaxies. The total number of particles is 1.2×108for our high resolution run. The gravitational softening is 5 pc and we allow gas to cool down to ~10 K. During the first encounter of the collision, a giant filament consists of cold and dense gas found between the progenitors by shock compression. A vigorous starburst took place in the filament, resulting in the formation of star clusters. The mass of these star clusters ranges from 105−8M⊙. These star clusters formed hierarchically: at first small star clusters formed, and then they merged via gravity, resulting in larger star clusters.

scholarly journals Correlations between H α equivalent width and galaxy properties at z = 0.47: Physical or selection-driven?

2021 ◽  
Vol 503 (4) ◽  
pp. 5115-5133
Author(s):  
A A Khostovan ◽  
S Malhotra ◽  
J E Rhoads ◽  
S Harish ◽  
C Jiang ◽  
...  
Keyword(s):  
Star Formation ◽  
Equivalent Width ◽  
Luminosity Function ◽  
Mass Function ◽  
Stellar Mass ◽  
High Mass ◽  
Selection Effects ◽  
Star Formation Activity ◽  
Low Mass ◽  
Stellar Masses

ABSTRACT The H α equivalent width (EW) is an observational proxy for specific star formation rate (sSFR) and a tracer of episodic, bursty star-formation activity. Previous assessments show that the H α EW strongly anticorrelates with stellar mass as M−0.25 similar to the sSFR – stellar mass relation. However, such a correlation could be driven or even formed by selection effects. In this study, we investigate how H α EW distributions correlate with physical properties of galaxies and how selection biases could alter such correlations using a z = 0.47 narrow-band-selected sample of 1572 H α emitters from the Ly α Galaxies in the Epoch of Reionization (LAGER) survey as our observational case study. The sample covers a 3 deg2 area of COSMOS with a survey comoving volume of 1.1 × 105 Mpc3. We assume an intrinsic EW distribution to form mock samples of H α emitters and propagate the selection criteria to match observations, giving us control on how selection biases can affect the underlying results. We find that H α EW intrinsically correlates with stellar mass as W0∝M−0.16 ± 0.03 and decreases by a factor of ∼3 from 107 M⊙ to 1010 M⊙, while not correcting for selection effects steepens the correlation as M−0.25 ± 0.04. We find low-mass H α emitters to be ∼320 times more likely to have rest-frame EW>200 Å compared to high-mass H α emitters. Combining the intrinsic W0–stellar mass correlation with an observed stellar mass function correctly reproduces the observed H α luminosity function, while not correcting for selection effects underestimates the number of bright emitters. This suggests that the W0–stellar mass correlation when corrected for selection effects is physically significant and reproduces three statistical distributions of galaxy populations (line luminosity function, stellar mass function, EW distribution). At lower stellar masses, we find there are more high-EW outliers compared to high stellar masses, even after we take into account selection effects. Our results suggest that high sSFR outliers indicative of bursty star formation activity are intrinsically more prevalent in low-mass H α emitters and not a byproduct of selection effects.

scholarly journals Massive Star Cluster Formation and Destruction in Luminous Infrared Galaxies in GOALS. II. An ACS/WFC3 Survey of Nearby LIRGs

2021 ◽  
Vol 923 (2) ◽  
pp. 278
Author(s):  
S. T. Linden ◽  
A. S. Evans ◽  
K. Larson ◽  
G. C. Privon ◽  
L. Armus ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Early Stage ◽  
Cluster Formation ◽  
Age Distribution ◽  
Star Clusters ◽  
Star Cluster ◽  
Wide Field ◽  
Infrared Galaxies ◽  
Luminous Infrared Galaxies ◽  
Cluster Age

Abstract We present the results of a Hubble Space Telescope WFC3 near-UV and Advanced Camera for Surveys Wide Field Channel optical study into the star cluster populations of a sample of 10 luminous infrared galaxies (LIRGs) in the Great Observatories All-Sky LIRG Survey. Through integrated broadband photometry we have derived ages, masses, and extinctions for a total of 1027 star clusters in galaxies with d L < 110 Mpc in order to avoid issues related to cluster bending. The measured cluster age distribution slope of dN / d τ ∝ τ − 0.5 + / − 0.12 is steeper than what has been observed in lower-luminosity star-forming galaxies. Further, differences in the slope of the observed cluster age distribution between inner- ( dN / d τ ∝ τ − 1.07 + / − 0.12 ) and outer-disk ( dN / d τ ∝ τ − 0.37 + / − 0.09 ) star clusters provide evidence of mass-dependent cluster destruction in the central regions of LIRGs driven primarily by the combined effect of strong tidal shocks and encounters with massive giant molecular clouds. Excluding the nuclear ring surrounding the Seyfert 1 nucleus in NGC 7469, the derived cluster mass function (CMF; dN / dM ∝ M α ) offers marginal evidence for a truncation in the power law at M t ∼ 2×106 M ⊙ for our three most cluster-rich sources, which are all classified as early stage mergers. Finally, we find evidence of a flattening of the CMF slope of dN / dM ∝ M − 1.42 ± 0.1 for clusters in late-stage mergers relative to early stage (α = −1.65 ± 0.02), which we attribute to an increase in the formation of massive clusters over the course of the interaction.

scholarly journals Star cluster formation and cloud dispersal by radiative feedback: dependence on metallicity and compactness

2020 ◽  
Vol 497 (3) ◽  
pp. 3830-3845 ◽  
Author(s):  
Hajime Fukushima ◽  
Hidenobu Yajima ◽  
Kazuyuki Sugimura ◽  
Takashi Hosokawa ◽  
Kazuyuki Omukai ◽  
...  
Keyword(s):  
Star Formation ◽  
Massive Stars ◽  
Cluster Formation ◽  
Star Clusters ◽  
Star Cluster ◽  
Star Forming ◽  
Dynamical Time ◽  
Low Metallicity ◽  
Higher Temperature ◽  
Dust Attenuation

ABSTRACT We study star cluster formation in various environments with different metallicities and column densities by performing a suite of 3D radiation hydrodynamics simulations. We find that the photoionization feedback from massive stars controls the star formation efficiency (SFE) in a star-forming cloud, and its impact sensitively depends on the gas metallicity Z and initial cloud surface density Σ. At Z = 1 Z⊙, SFE increases as a power law from 0.03 at Σ = 10 M⊙ pc−2 to 0.3 at $\Sigma = 300\,\mathrm{M}_{\odot }\, {\rm pc^{-2}}$. In low-metallicity cases $10^{-2}\!-\!10^{-1}\, \mathrm{Z}_{\odot }$, star clusters form from atomic warm gases because the molecule formation time is not short enough with respect to the cooling or dynamical time. In addition, the whole cloud is disrupted more easily by expanding H ii bubbles that have higher temperature owing to less efficient cooling. With smaller dust attenuation, the ionizing radiation feedback from nearby massive stars is stronger and terminate star formation in dense clumps. These effects result in inefficient star formation in low-metallicity environments: the SFE drops by a factor of ∼3 at Z = 10−2 Z⊙ compared to the results for Z = 1 Z⊙, regardless of Σ. Newborn star clusters are also gravitationally less bound. We further develop a new semi-analytical model that can reproduce the simulation results well, particularly the observed dependencies of the SFEs on the cloud surface densities and metallicities.

Efficiencies of Low‐Mass Star and Star Cluster Formation

2000 ◽  
Vol 545 (1) ◽  
pp. 364-378 ◽  
Author(s):  
Christopher D. Matzner ◽  
Christopher F. McKee
Keyword(s):  
Cluster Formation ◽  
Star Cluster ◽  
Mass Star ◽  
Low Mass

scholarly journals High-Mass Star and Massive Cluster Formation in the Milky Way

2018 ◽  
Vol 56 (1) ◽  
pp. 41-82 ◽  
Author(s):  
Frédérique Motte ◽  
Sylvain Bontemps ◽  
Fabien Louvet
Keyword(s):  
Star Formation ◽  
Milky Way ◽  
Galactic Plane ◽  
Cluster Formation ◽  
Theoretical Models ◽  
High Mass ◽  
High Angular Resolution ◽  
Mass Star ◽  
Star Forming ◽  
Massive Cluster

This review examines the state-of-the-art knowledge of high-mass star and massive cluster formation, gained from ambitious observational surveys, which acknowledges the multiscale characteristics of these processes. After a brief overview of theoretical models and main open issues, we present observational searches for the evolutionary phases of high-mass star formation, first among high-luminosity sources and more recently among young massive protostars and the elusive high-mass prestellar cores. We then introduce the most likely evolutionary scenario for high-mass star formation, which emphasizes the link of high-mass star formation to massive cloud and cluster formation. Finally, we introduce the first attempts to search for variations of the star-formation activity and cluster formation in molecular cloud complexes in the most extreme star-forming sites and across the Milky Way. The combination of Galactic plane surveys and high–angular resolution images with submillimeter facilities such as Atacama Large Millimeter Array (ALMA) are prerequisites to make significant progress in the forthcoming decade.

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