Volume 620, December 2018
|Number of page(s)||12|
|Section||Galactic structure, stellar clusters and populations|
|Published online||12 December 2018|
Mergers, tidal interactions, and mass exchange in a population of disc globular clusters⋆
1 GEPI, Observatoire de Paris, PSL Research University, CNRS, Place Jules Janssen, 92195 Meudon Cedex, France
2 Max Planck Institute for Extraterrestrial Physics, 85741 Garching, Germany
3 Max Planck Institute für Astronomie, Konigsthul 17, 69117 Heidelberg, Germany
Accepted: 10 September 2018
We present the results of a self-consistent N-body simulation following the evolution of a primordial population of thick-disc globular clusters (GCs). We study how the internal properties of such clusters evolve under the action of mutual interactions, while they orbit a Milky Way-like galaxy. For the first time, through analytical and numerical considerations, we find that physical encounters between disc GCs are a crucial factor that contributed to the shape of the current properties of the Galactic GC system. Close passages or motion on similar orbits may indeed have a significant impact on the internal structure of clusters, producing multiple gravitationally bound sub-populations through the exchange of mass and even mergers. Our model produces two major mergers and a few small mass exchanges between pairs of GCs. Two of our GCs accrete stars from two companions, ending up with three internal sub-populations. We propose these early interactions and mergers between thick disc GCs with slightly different initial chemical compositions as a possible explanation for the spreads in metallicity observed in some of the massive Milky Ways GCs.
Key words: galaxies: evolution / galaxies: kinematics and dynamics / galaxies: structure / globular clusters: general
High-resolution versions of the movies in Figs. 2, 5–7, A.1–A.2 are available at https://www.aanda.org
© ESO 2018
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