Kinematic characteristics of the Milky Way globular clusters based on Gaia DR2 data

Iryna Chemerynska, M. Ishchenko, Main Astronomical Observatory of NAS of Ukraine, M. Sobolenko, Main Astronomical Observatory of NAS of Ukraine, Хоперсков Сергей Александрович, Leibniz-Institut für Astrophysik Potsdam (AIP), Germany, Peter Berczik

2022

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DOI 10.17721/2227-1481.12.18-24

Data confidence 70 medium

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Abstract

Using the data from Gaia (ESA) Data Release 2 we performed the orbital calculations of globular clusters (GCs) of the Milky Way. To explore possible close encounters (or collisions) between the GCs, using our own developed high-order φ-GRAPE code, we integrated backward and forward orbits of 119 objects with reliable positions and proper motions. In the calculations, we adopted a realistic axisymmetric Galactic potential (bulge + disk + halo). Using different impact conditions, we found four pairs of six GCs that may have experienced an encounter within twice the sum of the half-mass radii ('collisions') over the last 5 Gyr: Terzan 3 — NGC 6553, Terzan 3 — NGC 6218, Liller 1 — NGC 6522 and Djorg 2 — NGC 6553.