Tidal Shocks on Globular Clusters

Léon, S.; Verdes–Montenegro, L.; Bergond, G.; Meylan, G.; Combes, F.

doi:10.1007/1-4020-2620-x_54

Cited by 183 publications

(314 citation statements)

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“…Most of weak field stars are then directly eliminated, whereas only the bottom of the OC main sequence (that is, most of Mermilliod 1995) http://obswww.unige.ch/webda/, except for the masses (particularly uncertain), which come from Bruch & Sanders (1983) for NGC 2287, or from late-type dwarf members) is missing. Keeping only bright OC members to minimize pollution also obviously decreases the number of detected stripped stars from the cluster, which are preferentially low mass stars, as noted both from observations (Leon et al 2000) and simulations (e.g., Combes et al 1999), but the S/N of the tidal tails relative to the background/foreground stars will be higher due to the richness of the three selected clusters.…”

Section: Resultsmentioning

confidence: 80%

“…about 0.1 mag both in B and B−R). We refer to the papers of Leon et al (1999Leon et al ( , 2000 for details of the application of the method. We then retain only cells where the number of cluster members with respect to the field stars is the highest, by defining a threshold we choose as a compromise between significant star-count (in order to prevent background fluctuations) and reduced contamination by field stars.…”

Section: Resultsmentioning

confidence: 99%

“…Terlevich (1987) and de la Fuente Marcos (1997 and references therein) performed realistic simulations of open cluster evolution. From the observational point of view, Grillmair et al (1995) and Leon et al (2000) detected important tidal tail extensions around galactic globular clusters using a wide-field star count analysis. Leon et al (1999) also found noticeable tidal tails around several binary star clusters in the Large Magellanic Cloud.…”

Section: Introductionmentioning

confidence: 99%

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Gravitational tidal effects on galactic open clusters

Bergond

Léon

Guibert

2001

A&A

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Abstract.We have investigated the 2-D stellar distribution in the outer parts of three nearby open clusters: NGC 2287 (≡M 41), NGC 2516, and NGC 2548 (≡M 48). Wide-field star counts have been performed in two colours on pairs of digitized ESO and SRC Schmidt plates, allowing us to select likely cluster members in the colour-magnitude diagrams. Cluster tidal extensions were emphasized using a wavelet transform. Taking into account observational biases, namely the galaxy clustering and differential extinction in the Galaxy, we have associated these stellar overdensities with real open cluster structures stretched by the galactic gravitational field. As predicted by theory and simulations, and despite observational limitations, we detected a general elongated (prolate) shape in a direction parallel to the galactic Plane, combined with tidal tails extended perpendicularly to it. This geometry is due both to the static galactic tidal field and the heating up of the stellar system when crossing the Disk. The time varying tidal field will deeply affect the cluster dynamical evolution, and we emphasize the importance of adiabatic heating during the Disk-shocking. In the case of NGC 2548, our dating of the last shocking with the Plane (based on a tidal clump) is consistent with its velocity. During the 10-20 Z-oscillations experienced by a cluster before its dissolution in the Galaxy, crossings through the galactic Disk contribute to at least 15% of the total mass loss. Using recent age estimations published for open clusters, we find a destruction time-scale of about 600 Myr for clusters in the solar neighbourhood.

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Section: Resultsmentioning

confidence: 80%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gravitational tidal effects on galactic open clusters

Bergond

Léon

Guibert

2001

A&A

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“…Since the period of rotation of ω Centauri is 120 Myr (Dinescu et al 1999), this plane crossing is likely to happen every 60 Myr. Leon et al (2000) have found evidence for disc shocking in ω Centauri, in the form of a tidal tail aligned with the tidal field gradient. The stars formed in this way will show little mean rotation, if any.…”

Section: Origin Of the Enriched Gasmentioning

confidence: 96%

Stellar populations in ω Centauri: a multivariate analysis

Fraix-Burnet¹,

Davoust²

2015

Monthly Notices of the Royal Astronomical Society

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We have performed multivariate statistical analyses of photometric and chemical abundance parameters of three large samples of stars in the globular cluster ω Centauri. The statistical analysis of a sample of 735 stars based on seven chemical abundances with the method of Maximum Parsimony (cladistics) yields the most promising results: seven groups are found, distributed along three branches with distinct chemical, spatial and kinematical properties. A progressive chemical evolution can be traced from one group to the next, but also within groups, suggestive of an inhomogeneous chemical enrichment of the initial interstellar matter. The adjustment of stellar evolution models shows that the groups with metallicities [Fe/H]> -1.5 are Helium-enriched, thus presumably of second generation. The spatial concentration of the groups increases with chemical evolution, except for two groups, which stand out in their other properties as well. The amplitude of rotation decreases with chemical evolution, except for two of the three metal-rich groups, which rotate fastest, as predicted by recent hydrodynamical simulations. The properties of the groups are interpreted in terms of star formation in gas clouds of different origins. In conclusion, our multivariate analysis has shown that metallicity alone cannot segregate the different populations of ω Centauri.

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“…This cluster should suffer regular disk shocking and should display some scars from this phenomenon, like, e.g., tidal tails. Leon et al (2000) studied the 2-D structures of the distribution of stars around w Cen and 19 Galactic globular clusters, using wide field imaging observations with field of view 5.5° x 5.5°. For each field, a (B vs. B -V) color-magnitude diagram was constructed, on which a field/cluster star selection was performed, following the pioneering method of Grillmair etal.…”

Section: Tidal Tails Around Galactic Globular Clustersmentioning

confidence: 99%