The orbital motion of the Arches cluster — clues on cluster formation near the galactic center

Abstract

Abstract. The Arches cluster is one of the most massive, young clusters in the Milky Way. Located inside the central molecular zone in the inner 200 pc of the Galactic center, it formed in one of the most extreme star-forming environments in the present-day Galaxy. Its young age of only 2.5 Myr allows us to observe the cluster despite the strong tidal shear forces in the inner Galaxy. The orbit of the cluster determines its dynamical evolution, tidal stripping, and hence its fate. We have measured the proper motion of the Arches cluster relative to the ambient field from Keck/NIRC2 LGS-AO and VLT/NAOS-CONICA NGS-AO observations taken 4.3 years earlier. When combined with the radial velocity, we derive a 3D space motion of 232 ± 30 km/s for the Arches. This motion is exceptionally large when compared to molecular cloud orbits in the GC, and places stringent constraints on the formation scenarios for starburst clusters in dense, nuclear environments.

Isolated massive stars in the Galactic center: The dynamic contribution from the Arches and Quintuplet star clusters

“…Stolte et al (2008a) discussed the formation of the Arches cluster inside the central 200 pc of the Galaxy as one of the most likely formation scenarios. Furthermore, considering its orbital properties and the measured foreground extinction of the cluster, which is lower than the extinction found toward the central parsec, Stolte et al (2008a) concluded that the cluster is likely in front of the GC today. For the simulations, we therefore assume a line-of-sight location of d los = −100 pc in front of the GC at its present age of 2.5 Myr.…”

“…To study the mechanism allowing the sources to drift out of the cluster in more detail, we analyze the trajectories of the sources in different mass ranges and compare them to the position of the cluster on its orbit around the GC. Stolte et al (2008a) showed that the Arches cluster evolves along an open eccentric rosetta-like orbit (see Figs. 9a and A.1a).…”