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 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 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 Low-mass star formation and subclustering in the H II regions RCW 32, 33, and 27 of the Vela Molecular Ridge

2018 ◽  
Vol 617 ◽  
pp. A63 ◽  
Author(s):  
L. Prisinzano ◽  
F. Damiani ◽  
M. G. Guarcello ◽  
G. Micela ◽  
S. Sciortino ◽  
...  
Keyword(s):  
Star Formation ◽  
Cluster Formation ◽  
Large Population ◽  
Circumstellar Disks ◽  
Theoretical Models ◽  
Young Stellar Objects ◽  
Mass Star ◽  
Northwestern Region ◽  
Low Mass ◽  
Young Clusters

Context. Most stars are born in clusters, and recent results suggest that star formation (SF) preferentially occurs in subclusters. Studying the morphology and SF history of young clusters is crucial for understanding early cluster formation processes. Aims. We aim to identify the embedded population of young stellar objects (YSOs) down to the low-mass stars in the M-type regime in the three H II regions RCW 33, RCW 32, and RCW 27, which are located in the northwestern region of the Vela Molecular Ridge. Our aim is to characterize their properties, such as morphology and extent of the clusters in the three H II regions, derive stellar ages, and determine the connection of the SF history with the environment. Methods. Through public photometric surveys such as Gaia, VPHAS+, 2MASS, and Spitzer/GLIMPSE, we identify YSOs with classical techniques aimed at detecting IR, Hα, and UV excesses as signatures of circumstellar disks and accretion. In addition, we implement a method for distinguishing main-sequence (MS) stars and giants in the M-type regime by comparing the reddening derived in several optical/IR color-color diagrams, assuming suitable theoretical models. Since this diagnostic is sensitive to stellar gravity, the procedure allows us to also identify pre-MS (PMS) stars. Results. Using the classical membership criteria, we find that a large population of YSOs shows signatures of circumstellar disks with or without accretion. In addition, with the new technique of M-type star selection, we find a rich population of young M-type stars whose spatial distribution strongly correlates with the more massive population. We find evidence of three young clusters, with different morphology, for which we estimate the individual distances using TGAS Gaia data of the brighter subsample. In addition, we identify field stars falling in the same region by securely classifying them as giants and foreground MS stars. Conclusions. We identify the embedded population of YSOs down to about 0.1 M⊙ that is associated with the three H II regions RCW 33, RCW 32, and RCW 27 and the three clusters Vela T2, Cr 197, and Vela T1, respectively. All the three clusters are located at a similar distance, but they have very different morphologies. Our results suggest a decreasing SF rate in Vela T2 and triggered SF in Cr 197 and Vela T1.

scholarly journals Implementing Primordial Binaries in Simulations of Star Cluster Formation with a Hybrid MHD and Direct N-Body Method

2020 ◽  
Author(s):  
Claude Cournoyer-Cloutier ◽  
Aaron Tran ◽  
Sean Lewis ◽  
Joshua E Wall ◽  
William E Harris ◽  
...  
Keyword(s):  
Binary Systems ◽  
Binary Star ◽  
Cluster Formation ◽  
Dynamical Evolution ◽  
Star Cluster ◽  
Initial Population ◽  
Mass Ratios ◽  
Low Mass ◽  
Initial Distributions ◽  
Body Method

Abstract The fraction of stars in binary systems within star clusters is important for their evolution, but what proportion of binaries form by dynamical processes after initial stellar accretion remains unknown. In previous work, we showed that dynamical interactions alone produced too few low-mass binaries compared to observations. We therefore implement an initial population of binaries in the coupled MHD and direct N-body star cluster formation code Torch. We compare simulations with, and without, initial binary populations and follow the dynamical evolution of the binary population in both sets of simulations, finding that both dynamical formation and destruction of binaries take place. Even in the first few million years of star formation, we find that an initial population of binaries is needed at all masses to reproduce observed binary fractions for binaries with mass ratios above the q ≥ 0.1 detection limit. Our simulations also indicate that dynamical interactions in the presence of gas during cluster formation modify the initial distributions towards binaries with smaller primary masses, larger mass ratios, smaller semi-major axes and larger eccentricities. Systems formed dynamically do not have the same properties as the initial systems, and systems formed dynamically in the presence of an initial population of binaries differ from those formed in simulations with single stars only. Dynamical interactions during the earliest stages of star cluster formation are important for determining the properties of binary star systems.

scholarly journals Stellar and brown dwarf properties from numerical simulations

2009 ◽  
Vol 5 (H15) ◽  
pp. 769-770
Author(s):  
Matthew R. Bate
Keyword(s):  
Numerical Simulations ◽  
Cluster Formation ◽  
Brown Dwarfs ◽  
Star Cluster ◽  
Statistical Properties ◽  
Brown Dwarf ◽  
Hydrodynamical Simulation ◽  
Low Mass

AbstractWe review the statistical properties of stars and brown dwarfs obtained from the first hydrodynamical simulation of star cluster formation to produce more than a thousand stars and brown dwarfs while simultaneously resolving the lowest mass brown dwarfs (those with masses set by the opacity limit for fragmentation), binaries with separations down to ~ 1 AU, and discs with radii greater than ~ 10 AU. In particular, we present the eccentricity distribution of the calculation's very-low-mass and brown dwarf binaries which has not been previously published.

scholarly journals There is no magnetic braking catastrophe: low-mass star cluster and protostellar disc formation with non-ideal magnetohydrodynamics

2019 ◽  
Vol 489 (2) ◽  
pp. 1719-1741 ◽  
Author(s):  
James Wurster ◽  
Matthew R Bate ◽  
Daniel J Price
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Large Scale ◽  
Star Cluster ◽  
Mass Star ◽  
Low Mass ◽  
Ideal Magnetohydrodynamics ◽  
Protostellar Discs ◽  
Disc Formation

Abstract We present results from the first radiation non-ideal magnetohydrodynamics (MHD) simulations of low-mass star cluster formation that resolve the fragmentation process down to the opacity limit. We model 50 M⊙ turbulent clouds initially threaded by a uniform magnetic field with strengths of 3, 5 10, and 20 times the critical mass-to-magnetic flux ratio, and at each strength, we model both an ideal and non-ideal (including Ohmic resistivity, ambipolar diffusion, and the Hall effect) MHD cloud. Turbulence and magnetic fields shape the large-scale structure of the cloud, and similar structures form regardless of whether ideal or non-ideal MHD is employed. At high densities (106 ≲ nH ≲ 1011 cm−3), all models have a similar magnetic field strength versus density relation, suggesting that the field strength in dense cores is independent of the large-scale environment. Albeit with limited statistics, we find no evidence for the dependence of the initial mass function on the initial magnetic field strength, however, the star formation rate decreases for models with increasing initial field strengths; the exception is the strongest field case where collapse occurs primarily along field lines. Protostellar discs with radii ≳ 20 au form in all models, suggesting that disc formation is dependent on the gas turbulence rather than on magnetic field strength. We find no evidence for the magnetic braking catastrophe, and find that magnetic fields do not hinder the formation of protostellar discs.

scholarly journals Comparison of Low-Mass and High-Mass Star Formation

2015 ◽  
Vol 11 (S315) ◽  
pp. 154-162 ◽  
Author(s):  
Jonathan C. Tan
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Initial Conditions ◽  
Cluster Formation ◽  
Theoretical Models ◽  
High Mass ◽  
Mass Star ◽  
Massive Star Formation ◽  
Low Mass ◽  
Core Accretion

AbstractI review theoretical models of star formation and how they apply across the stellar mass spectrum. Several distinct theories are under active study for massive star formation, especiallyTurbulent Core Accretion,Competitive AccretionandProtostellar Mergers, leading to distinct observational predictions. These include the types of initial conditions, the structure of infall envelopes, disks and outflows, and the relation of massive star formation to star cluster formation. Even for Core Accretion models, there are several major uncertainties related to the timescale of collapse, the relative importance of different processes for preventing fragmentation in massive cores, and the nature of disks and outflows. I end by discussing some recent observational results that are helping to improve our understanding of these processes.

Low‐Mass Star Formation and the Initial Mass Function in IC 348

1998 ◽  
Vol 508 (1) ◽  
pp. 347-369 ◽  
Author(s):  
K. L. Luhman ◽  
G. H. Rieke ◽  
C. J. Lada ◽  
E. A. Lada
Keyword(s):  
Star Formation ◽  
Mass Function ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Mass Star ◽  
Low Mass
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