Evolution of fractality and rotation in embedded star clusters

Ballone, Alessandro; Mapelli, Michela; Carlo, Ugo N. Di; Torniamenti, Stefano; Spera, M.; Rastello, Sara

doi:10.1093/mnras/staa1383

Cited by 42 publications

(39 citation statements)

References 88 publications

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“…Hénault-Brunet et al 2012;Cottaar et al 2015). Simulations, however, suggest that rotation in young clusters should be common (e.g Mapelli 2017; Ballone et al 2020).…”

Section: Angular Momentummentioning

confidence: 99%

Collision between molecular clouds – I. The effect of the cloud virial ratio in head-on collisions

Tanvir

Dale

2020

Monthly Notices of the Royal Astronomical Society

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In a series of papers we investigate the effect of collisions between turbulent molecular clouds on their structure, evolution and star formation activity. In this paper we look into the role of the clouds' initial virial ratios. Three different scenarios were examined: both clouds initially bound, one cloud bound and one unbound, and both clouds initially unbound. Models in which one or both clouds are bound generate filamentary structures aligned along the collision axis and discernible in position-position and position-velocity space. If neither cloud is bound, no filaments result. Unlike in previous simulations of collisions between smooth clouds, owing to the substructure created in the clouds by turbulence before the collisions, dissipation of kinetic energy by the collision is very inefficient and in none of our simulations is sufficient bulk kinetic energy lost to render the clouds bound. Simulations where both clouds are bound created twice as much stellar mass than the bound-unbound model, and both these scenarios produced much more stellar mass than the simulation in which both clouds are unbound. Each simulation was also compared with a control run in which the clouds do not collide. We find the bound-bound collision increases the overall star formation efficiency by a factor of approximately two relative to the control, but that the bound-unbound collision produces a much smaller increase, and the collision has very little effect on the unbound-unbound cloud collision.

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“…Hénault-Brunet et al 2012;Cottaar et al 2015). Simulations, however, suggest that rotation in young clusters should be common (e.g Mapelli 2017; Ballone et al 2020).…”

Section: Angular Momentummentioning

confidence: 99%

Collision between molecular clouds – I. The effect of the cloud virial ratio in head-on collisions

Tanvir

Dale

2020

Monthly Notices of the Royal Astronomical Society

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“…Studies of clusters' formation and very early evolution have shown that clusters can emerge from these evolutionary phases with dynamical properties characterized by mass segregation, internal rotation, and radial anisotropy in the velocity distribution; the detailed role of different dynamical processes acting during these phases and the variety of different dynamical paths resulting in these dynamical properties are still matter of intense investigation (see e.g. Goodwin & Whitworth 2004, McMillan et al 2007, Allison et al 2009, 2010, Moeckel & Bonnell 2009, Fujii et al 2012, Fujii & Portegies Zwart 2016, Vesperini et al 2014, Parker et al 2016, Domínguez et al 2017, Mapelli 2017, Banerjee & Kroupa 2014, 2017, Sills et al 2018, Daffern-Powell & Parker 2020, Ballone et al 2020, Ballone et al 2021.…”

Section: Introductionmentioning

confidence: 99%

Early dynamics and violent relaxation of multimass rotating star clusters

Livernois

Vesperini

Tiongco

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present the results of a study aimed at exploring, by means of N-body simulations, the evolution of rotating multi-mass star clusters during the violent relaxation phase, in the presence of a weak external tidal field. We study the implications of the initial rotation and the presence of a mass spectrum for the violent relaxation dynamics and the final properties of the equilibria emerging at the end of this stage. Our simulations show a clear manifestation of the evolution towards spatial mass segregation and evolution towards energy equipartition during and at the end of the violent relaxation phase. We study the final rotational kinematics and show that massive stars tend to rotate more rapidly than low-mass stars around the axis of cluster rotation. Our analysis also reveals that during the violent relaxation phase, massive stars tend to preferentially segregate into orbits with angular momentum aligned with the cluster’s angular momentum, an effect previously found in the context of the long-term evolution of star clusters driven by two-body relaxation.

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“…Rotation in massive star clusters affects their evolution, as net angular momentum may speed up the core collapse and increase the escape rate of stars (Einsel & Spurzem 1999;Ernst et al 2007;Hong et al 2013;Chen et al 2020). Hydrodynamical studies at individual cloud-scales, even without external dynamical effects such as a surrounding live galaxy, find it extremely difficult to produce non-rotating clusters (Lee & Hennebelle 2016a;Ballone et al 2020) with only very low-mass (e.g. < 100 M , Mapelli 2017) clusters exhibiting no clear rotational signatures.…”

Section: Introductionmentioning

confidence: 99%

Structure and Rotation of Young Massive Star Clusters in a Simulated Dwarf Starburst

Lahén

Naab

Johansson

et al. 2020

ApJ

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We analyze the three-dimensional shapes and kinematics of the young star cluster population forming in a high-resolution griffin project simulation of a metal-poor dwarf galaxy starburst. The star clusters, which follow a power-law mass distribution, form from the cold ISM phase with an IMF sampled with individual stars down to 4 solar masses at sub-parsec spatial resolution. Massive stars and their important feedback mechanisms are modelled in detail. The simulated clusters follow a surprisingly tight relation between the specific angular momentum and mass with indications of two sub-populations. Massive clusters (M cl 3 × 10 4 M ) have the highest specific angular momenta at low ellipticities ( ∼ 0.2) and show alignment between their shapes and rotation. Lower mass clusters have lower specific angular momenta with larger scatter, show a broader range of elongations, and are typically misaligned indicating that they are not shaped by rotation. The most massive clusters (M 10 5 M ) accrete gas and proto-clusters from a 100 pc scale local galactic environment on a t 10 Myr timescale, inheriting the ambient angular momentum properties. Their two-dimensional kinematic maps show ordered rotation at formation, up to v ∼ 8.5 kms −1 , consistent with observed young massive clusters and old globular clusters, which they might evolve into. The massive clusters have angular momentum parameters λ R 0.5 and show Gauss-Hermite coefficients h 3 that are anticorrelated with the velocity, indicating asymmetric line-of-sight velocity distributions as a signature of a dissipative formation process.

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Evolution of fractality and rotation in embedded star clusters

Cited by 42 publications

References 88 publications

Collision between molecular clouds – I. The effect of the cloud virial ratio in head-on collisions

Collision between molecular clouds – I. The effect of the cloud virial ratio in head-on collisions

Early dynamics and violent relaxation of multimass rotating star clusters

Structure and Rotation of Young Massive Star Clusters in a Simulated Dwarf Starburst

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