SIMBAD references

1999A&A...344..450L - Astronomy and Astrophysics, volume 344, 450-458 (1999/4-2)

Interacting star clusters in the Large Magellanic Cloud. Overmerging problem solved by cluster group formation.

LEON S., BERGOND G. and VALLENARI A.

Abstract (from CDS):

We present the tidal tail distributions of a sample of candidate binary clusters located in the bar of the Large Magellanic Cloud (LMC). One isolated cluster, SL 268, is presented in order to study the effect of the LMC tidal field. All the candidate binary clusters show tidal tails, confirming that the pairs are formed by physically linked objects. The stellar mass in the tails covers a large range, from 1.8x103 to 3x104M. We derive a total mass estimate for SL 268 and SL 356. At large radii, the projected density profiles of SL 268 and SL 356 fall off as r–γ, with γ=2.27 and γ=3.44, respectively. Out of 4 pairs or multiple systems, 2 are older than the theoretical survival time of binary clusters (going from a few 106 years to 108 years). A pair shows too large age difference between the components to be consistent with classical theoretical models of binary cluster formation (Fujimoto & Kumai, 1997AJ....113..249F). We refer to this as the ``overmerging'' problem. A different scenario is proposed: the formation proceeds in large molecular complexes giving birth to groups of clusters over a few 107 years. In these groups the expected cluster encounter rate is larger, and tidal capture has higher probability. Cluster pairs are not born together through the splitting of the parent cloud, but formed later by tidal capture. For 3 pairs, we tentatively identify the star cluster group (SCG) memberships. The SCG formation, through the recent cluster starburst triggered by the LMC-SMC encounter, in contrast with the quiescent open cluster formation in the Milky Way can be an explanation to the paucity of binary clusters observed in our Galaxy.

Abstract Copyright:

Journal keyword(s): stars: formation - stars: Hertzsprung-Russel (HR) and C-M diagrams - galaxies: Magellanic Clouds - galaxies: star clusters - galaxies: stellar content

Simbad objects: 23

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