scholarly journals From hydrodynamics to N-body simulations of star clusters: mergers and rotation

2020 ◽  
Author(s):  
Alessandro Ballone ◽  
Stefano Torniamenti ◽  
Michela Mapelli ◽  
Ugo N Di Carlo ◽  
Mario Spera ◽  
...  
Keyword(s):  
Initial Conditions ◽  
Star Clusters ◽  
Mass Function ◽  
Young Star ◽  
Initial Mass Function ◽  
Early Evolution ◽  
Stellar Feedback ◽  
Gas Removal ◽  
Hydrodynamical Simulations ◽  
Young Star Clusters

Abstract We present a new method to obtain more realistic initial conditions for N-body simulations of young star clusters. We start from the outputs of hydrodynamical simulations of molecular cloud collapse, in which star formation is modelled with sink particles. In our approach, we instantaneously remove gas from these hydrodynamical simulation outputs to mock the end of the gas-embedded phase, induced by stellar feedback. We then enforce a realistic initial mass function by splitting or joining the sink particles based on their mass and position. Such initial conditions contain more consistent information on the spatial distribution and the kinematical and dynamical states of young star clusters, which are fundamental to properly study these systems. For example, by applying our method to a set of previously run hydrodynamical simulations, we found that the early evolution of young star clusters is affected by gas removal and by the early dry merging of sub-structures. This early evolution can either quickly erase the rotation acquired by our (sub-)clusters in their embedded phase or “fuel” it by feeding of angular momentum by sub-structure mergers, before two-body relaxation acts on longer timescales.

scholarly journals The Mass Function of Young Star Clusters in our Galaxy and Nearby Galaxies: Is It Universal?

2002 ◽  
Vol 207 ◽  
pp. 515-524
Author(s):  
Ram Sagar
Keyword(s):  
Star Clusters ◽  
Dynamical Evolution ◽  
Mass Function ◽  
Young Star ◽  
Initial Mass Function ◽  
Galactocentric Distance ◽  
Photometric Observations ◽  
Nearby Galaxies ◽  
Mass Segregation ◽  
Young Star Clusters

Mass functions (MFs) derived from photometric observations of young star clusters of our Galaxy, the Magellanic Clouds (MCs), M31 and M33 have been used to investigate the question of universality of the initial mass function and presence of mass segregation in these systems. Observational determination of the MF slope of young star clusters have an inherent uncertainty of at least ∼ 1.0 dex in the Milky Way and of ∼ 0.4 dex in the MCs. There is no obvious dependence of the MF slope on either galactocentric distance or age of the young star clusters or on the spatial concentration of the stars formed or on the galactic characteristics including metallicity. Effects of mass segregation have been observed in a good number of young stellar groups of our Galaxy and MCs. As their ages are much smaller than their dynamical evolution times, star formation processes seem to be responsible for the observed mass segregation in them.

scholarly journals The Initial Mass Function in Young Star Clusters

1986 ◽  
Vol 7 ◽  
pp. 489-499
Author(s):  
Hans Zinnecker
Keyword(s):  
Star Formation ◽  
Recent Work ◽  
Star Clusters ◽  
Mass Function ◽  
Young Star ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Stellar Content ◽  
Young Star Clusters ◽  
The Imf

AbstractThis review discusses both the earlier and the most recent work on the IMF in young star clusters. It is argued that the study of the stellar content of young star clusters offers the best chance of developing a theory of star formation and of the IMF.

scholarly journals Young Star Clusters in the LMC

1992 ◽  
Vol 45 (4) ◽  
pp. 407
Author(s):  
KC Freeman
Keyword(s):  
Mass Loss ◽  
Globular Clusters ◽  
Star Clusters ◽  
Dynamical Evolution ◽  
Mass Function ◽  
Young Star ◽  
Stellar Mass ◽  
Initial Mass Function ◽  
Initial Mass ◽  
Young Star Clusters

The young globular star clusters in the LMC offer us insights into the formation and early dynamical evolution of globular clusters which are unobtainable from the old globular clusters in our Galaxy. Because these young clusters are so young and populous, they provide an opportunity to measure the upper end of the initial mass function by direct means and also through the dynamical effects of stellar mass loss on the structure of the clusters.

scholarly journals Dynamical Masses of Young Star Clusters: Constraints on the Stellar IMF and Star-Formation Efficiency

2007 ◽  
Vol 3 (S246) ◽  
pp. 32-35
Author(s):  
N. Bastian
Keyword(s):  
Star Formation ◽  
Mass Function ◽  
Young Star ◽  
Initial Mass Function ◽  
Gas Removal ◽  
Stellar Initial Mass Function ◽  
Rapid Removal ◽  
Young Clusters ◽  
Formation Efficiency ◽  
Young Star Clusters

AbstractThrough the use of detailed light profiles and dynamical measurements of young clusters we investigate claims that the stellar initial mass function within clusters varies greatly. We find a strong age dependence in the clusters which have been claimed to have non-standard stellar IMFs, and suggest that the lack of equilibrium of these clusters is responsible for their ‘strange’ light-to-mass ratios and not IMF variations. The most likely culprit is the rapid removal of residual gas left over from the star-formation process which leaves the clusters severely out of dynamical equilibrium. By comparing the observations to N-body simulations we quantify to what degree a cluster is out of equilibrium and consequently its survival chances. We find that >60% of young clusters will be disrupted, due gas removal, within the first 20–50 Myr of their lives.

scholarly journals STELLAR FEEDBACK IN MOLECULAR CLOUDS AND ITS INFLUENCE ON THE MASS FUNCTION OF YOUNG STAR CLUSTERS

2010 ◽  
Vol 710 (2) ◽  
pp. L142-L146 ◽  
Author(s):  
S. Michael Fall ◽  
Mark R. Krumholz ◽  
Christopher D. Matzner
Keyword(s):  
Molecular Clouds ◽  
Star Clusters ◽  
Mass Function ◽  
Young Star ◽  
Stellar Feedback ◽  
Young Star Clusters

scholarly journals Evolution of fractality and rotation in embedded star clusters

2020 ◽  
Vol 496 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Alessandro Ballone ◽  
Michela Mapelli ◽  
Ugo N Di Carlo ◽  
Stefano Torniamenti ◽  
Mario Spera ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Molecular Clouds ◽  
Star Clusters ◽  
Young Star ◽  
Direct Result ◽  
Molecular Gas ◽  
Stellar Systems ◽  
Small Scales ◽  
Hydrodynamical Simulations ◽  
Young Star Clusters

ABSTRACT More and more observations indicate that young star clusters could retain imprints of their formation process. In particular, the degree of substructuring and rotation are possibly the direct result of the collapse of the parent molecular cloud from which these systems form. Such properties can, in principle, be washed-out, but they are also expected to have an impact on the relaxation of these systems. We ran and analysed a set of 10 hydrodynamical simulations of the formation of embedded star clusters through the collapse of turbulent massive molecular clouds. We systematically studied the fractality of our star clusters, showing that they are all extremely substructured (fractal dimension D = 1.0–1.8). We also found that fractality is slowly reduced, with time, on small scales, while it persists on large scales on longer time-scales. Signatures of rotation are found in different simulations at every time of the evolution, even for slightly supervirial substructures, proving that the parent molecular gas transfers part of its angular momentum to the new stellar systems.

scholarly journals Rapid mass segregation in young star clusters without substructure?

2010 ◽  
Vol 6 (S271) ◽  
pp. 389-390
Author(s):  
C. Olczak ◽  
R. Spurzem ◽  
Th. Henning
Keyword(s):  
Initial Conditions ◽  
Star Clusters ◽  
Building Blocks ◽  
Young Star ◽  
Subsequent Formation ◽  
Multiple Systems ◽  
Mass Segregation ◽  
New Generation ◽  
The Impact ◽  
Young Star Clusters

AbstractThe young star clusters we observe today are the building blocks of a new generation of stars and planets in our Galaxy and beyond. Despite their fundamental role we still lack knowledge about the initial conditions under which star clusters form and the impact of these often harsh environments on the formation and evolution of their stellar and substellar members.We present recent results showing that mass segregation in realistic models of young star clusters occurs very quickly for subvirial spherical systems without substructure. This finding is a critical step to resolve the controversial debate on mass segregation in young star clusters and provides strong constraints on their initial conditions. The rapid concentration of massive stars is usually associated with strong gravitational interactions early on during cluster evolution and the subsequent formation of multiple systems and ejection of stars.

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