Kinematical evolution of tidally limited star clusters: rotational properties

Tiongco, Maria; Vesperini, Enrico; Varri, Anna Lisa

doi:10.1093/mnras/stx853

Cited by 53 publications

(42 citation statements)

References 2 publications

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“…1. In agreement with previous findings (e.g., see Einsel & Spurzem 1999;Ernst et al 2007;Hong et al 2013;Tiongco et al 2017), the overall rotation in the system decreases in magnitude over time, as determined by a general redistribution and loss of angular momentum in the system due to relaxation effects. As the system evolves, it gradually loses its intrinsic differential rotation and evolves towards a configuration dominated by an approximately solid-body rotation about the z-axis with angular speed equal to about 0.5Ω (models XZRLOC and XZRUNL take longer to converge to this value than the time shown in Fig.…”

Section: Resultssupporting

confidence: 93%

The complex kinematics of rotating star clusters in a tidal field

Tiongco¹,

Vesperini²,

Varri³

2018

Monthly Notices of the Royal Astronomical Society: Letters

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We broaden the investigation of the dynamical properties of tidally perturbed, rotating star clusters by relaxing the traditional assumptions of coplanarity, alignment, and synchronicity between the internal and orbital angular velocity vector of their initial conditions. We show that the interplay between the internal evolution of these systems and their interaction with the external tidal field naturally leads to the development of a number of evolutionary features in their three-dimensional velocity space, including a precession and nutation of the global rotation axis and a variation of its orientation with the distance from the cluster centre. In some cases, such a radial variation may manifest itself as a counter-rotation of the outermost regions relative to the inner ones. The projected morphology of these systems is characterized by a non-monotonic ellipticity profile and, depending on the initial inclination of the rotation axis, it may also show a twisting of the projected isodensity contours. These results provide guidance in the identification of non-trivial features which may emerge in upcoming investigations of star cluster kinematics and a dynamical framework to understand some of the complexities already hinted by recent observational studies.

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Section: Resultssupporting

confidence: 93%

The complex kinematics of rotating star clusters in a tidal field

Tiongco¹,

Vesperini²,

Varri³

2018

Monthly Notices of the Royal Astronomical Society: Letters

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“…The ratio of r max /r h is in agreement with both theoretical models (e.g. Tiongco et al 2017) and observations in other clusters (e.g. Bianchini et al 2018).…”

Section: Kinematicssupporting

confidence: 90%

The peculiar kinematics of the multiple populations in the globular cluster Messier 80 (NGC 6093)

Kamann

Dalessandro²,

Bastian

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We combine MUSE spectroscopy and Hubble Space Telescope ultraviolet (UV) photometry to perform a study of the chemistry and dynamics of the Galactic globular cluster Messier 80 (M80, NGC 6093). Previous studies have revealed three stellar populations that not only vary in their light-element abundances, but also in their radial distributions, with concentration decreasing with increasing nitrogen enrichment. This remarkable trend, which sets M80 apart from the other Galactic globular clusters, points towards a complex formation and evolutionary history. To better understand how M80 formed and evolved, revealing its internal kinematics is key. We find that the most N-enriched population rotates faster than the other two populations at a 2σ confidence level. While our data further suggest that the intermediate population shows the least amount of rotation, this trend is rather marginal (1 − 2σ). Using axisymmetric Jeans models, we show that these findings can be explained from the radial distributions of the populations if they possess different angular momenta. Our findings suggest that the populations formed with primordial kinematical differences.

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“…After the rotational profiles of the two populations become indistinguishable, they share the same evolution towards smaller values of the rotational velocity, eventually converging towards a solid-body rotation, in agreement with what found in Tiongco et al (2016bTiongco et al ( , 2017. As shown in Tiongco et al (2016b), the combined effects due to the external tidal field and the preferential loss of prograde orbiting stars result in an internal rotation only partially synchronized with the external orbital rotation with an internal angular velocity ω 0.5Ω (see also Claydon et al 2017).…”

Section: Case Of the Rotation Axis Parallel To The Orbital Angular Vesupporting

confidence: 86%

Kinematical evolution of multiple stellar populations in star clusters

Tiongco

Vesperini

Varri

2019

Monthly Notices of the Royal Astronomical Society

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We present the results of a suite of N-body simulations aimed at understanding the fundamental aspects of the long-term evolution of the internal kinematics of multiple stellar populations in globular clusters. Our models enable us to study the cooperative effects of internal, relaxation-driven processes and external, tidally-induced perturbations on the structural and kinematic properties of multiple-population globular clusters. To analyse the dynamical behaviour of the multiple stellar populations in a variety of spin-orbit coupling conditions, we have considered three reference cases in which the tidally perturbed star cluster rotates along an axis oriented in different directions with respect to the orbital angular momentum vector. We focus specifically on the characterisation of the evolution of the degree of differential rotation and anisotropy in the velocity space, and we quantify the process of spatial and kinematic mixing of the two populations. In light of recent and forthcoming explorations of the internal kinematics of this class of stellar systems by means of line-of sight and astrometric measurements, we also investigate the implications of projection effects and spatial distribution of the stars adopted as tracers. The kinematic and structural richness emerging from our models further emphasises the need and the importance of observational studies aimed at building a complete kinematical picture of the multiple population phenomenon.1 Although we use the terms first-and second-generation to refer to the different populations, we point out that according to some formation models (see, e.g., Bastian et al. 2013, Gieles et al. 2018) all the populations form at the same time, and in those cases the two populations are more properly referred to as first-and second-population.

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Kinematical evolution of tidally limited star clusters: rotational properties

Cited by 53 publications

References 2 publications

The complex kinematics of rotating star clusters in a tidal field

The complex kinematics of rotating star clusters in a tidal field

The peculiar kinematics of the multiple populations in the globular cluster Messier 80 (NGC 6093)

Kinematical evolution of multiple stellar populations in star clusters

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