Formation and Evolution of Clumpy Tidal Tails around Globular Clusters

Dolcetta, R. Capuzzo; Matteo, P. Di; Miocchi, P.

doi:10.1086/426006

Cited by 65 publications

(74 citation statements)

References 43 publications

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“…3, one can also clearly see the so-called "tidal tail clumps" (star density enhancements) at about 150 pc from the cluster centre. These clumps were mentioned probably for the first time in Capuzzo Dolcetta et al (2005) and discussed in more detail by Küpper et al (2008). We observe these clumps in all our models (see the model videos at the FTP link shown in the footnote to page 809).…”

Section: Shape Parameters Of the Cluster Modelssupporting

confidence: 63%

Shape parameters of Galactic open clusters

Kharchenko

Berczik

Petrov

et al. 2009

A&A

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Context. Ellipticities have been determined for only a few tens of open clusters.Aims. We derive the observed and modelled shape parameters (apparent ellipticity and orientation of the ellipse) of 650 Galactic open clusters identified in the ASCC-2.5 catalogue. Methods. We compute the observed shape parameters of Galactic open clusters with a multi-component analysis. For the vast majority of clusters, these parameters are determined for the first time. High resolution ("star by star") N-body simulations are carried out with a specially developed φGRAPE code providing models of clusters of different initial masses, Galactocentric distances, and rotation velocities. Results. By comparing models and observations for about 150 clusters, we find that the ellipticities of observed clusters are too low (0.2 vs. 0.3), and take a first step in identifying the main reason for this discrepancy. After ≈50 Myr, the models predict that clusters exhibit an oblate shape with an axis ratio of 1.65:1.35:1, and a major axis tilt by an angle of q XY ≈ 30 • with respect to the Galactocentric radius due to the differential rotation of the Galaxy. Conclusions. Unbiased estimates of cluster shape parameters require reliable membership determination in large cluster areas out to 2−3 tidal radii, where the density of cluster stars is considerably lower than the background. Although dynamically bound stars beyond the tidal radius contribute insignificantly to the cluster mass, knowledge of their distribution is essential for a correct determination of cluster shape parameters. In contrast, a restricted mass range of cluster stars does not play such a dramatic role, although deep surveys allow us to identify more cluster members and, therefore, to increase the accuracy of the observed shape parameters.

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Section: Shape Parameters Of the Cluster Modelssupporting

confidence: 63%

Shape parameters of Galactic open clusters

Kharchenko

Berczik

Petrov

et al. 2009

A&A

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“…Leon et al 2000). Similar clumps were found by Capuzzo Dolcetta et al (2005) in N -body simulations of clusters on eccentric orbits. More recently, Küpper et al (2008) and carried out detailed studies of the orbits of escaping stars and showed that overdensities along the tails are expected even for clusters on circular orbits.…”

Section: (A) Mass Loss and Cluster Dissolutionsupporting

confidence: 86%

Star cluster dynamics

Vesperini

2010

Phil. Trans. R. Soc. A.

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Dynamical evolution plays a key role in shaping the current properties of star clusters and star cluster systems. A detailed understanding of the effects of evolutionary processes is essential to be able to disentangle the properties that result from dynamical evolution from those imprinted at the time of cluster formation. In this review, I focus my attention on globular clusters, and review the main physical ingredients driving their early and longterm evolution, describe the possible evolutionary routes and show how cluster structure and stellar content are affected by dynamical evolution.

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“…Star density distortions, elongation and tidal tails are expected to be detected also in the radial density profile (see for example Odenkirchen et al 2003;Capuzzo-Dolcetta et al 2005). Therefore as a second step of our analysis, we studied the projected density profile of NGC 6791.…”

Section: Star Density and Surface Brightness Profilesmentioning

confidence: 99%

Evidence of tidal distortions and mass-loss from the old open cluster NGC 6791

Dalessandro

Miocchi

Carraro³

et al. 2015

Monthly Notices of the Royal Astronomical Society

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We present the first evidence of clear signatures of tidal distortions in the density distribution of the fascinating open cluster NGC 6791. We used deep and wide-field data obtained with the Canada-France-Hawaii-Telescope covering a 2 • ×2 • area around the cluster. The two-dimensional density map obtained with the optimal matched filter technique shows a clear elongation and an irregular distribution starting from ∼ 300 ′′ from the cluster center. At larger distances, two tails extending in opposite directions beyond the tidal radius are also visible. These features are aligned to both the absolute proper motion and to the Galactic center directions. Moreover, other overdensities appear to be stretched in a direction perpendicular to the Galactic plane.Accordingly to the behaviour observed in the density map, we find that both the surface brightness and the star count density profiles reveal a departure from a King model starting from ∼ 600 ′′ from the center.These observational evidence suggest that NGC 6791 is currently experiencing mass loss likely due to gravitational shocking and interactions with the tidal field. We use this evidence to argue that NGC 6791 should have lost a significant fraction of its original mass. A larger initial mass would in fact explain why the cluster survived so long. Using available recipes based on analytic studies and N -body simulations, we derived the expected mass loss due to stellar evolution and tidal interactions and estimated the initial cluster mass to be M ini = (1.5-4) × 10 5 M ⊙ .

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Formation and Evolution of Clumpy Tidal Tails around Globular Clusters

Cited by 65 publications

References 43 publications

Shape parameters of Galactic open clusters

Shape parameters of Galactic open clusters

Star cluster dynamics

Evidence of tidal distortions and mass-loss from the old open cluster NGC 6791

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