On the Origin of High-Altitude Open Clusters in the Milky Way

Abstract

We present a dynamical study of the effect of the bar and spiral arms on the simulated orbits of open clusters in the Galaxy. Specifically, this work is devoted to the puzzling presence of high-altitude open clusters in the Galaxy. For this purpose we employ a very detailed observationally motivated potential model for the Milky Way and a careful set of initial conditions representing the newly born open clusters in the thin disk. We find that the spiral arms are able to raise an important percentage of open clusters (about one-sixth of the total employed in our simulations, depending on the structural parameters of the arms) above the Galactic plane to heights beyond 200 pc, producing a bulge-shaped structure toward the center of the Galaxy. Contrary to what was expected, the spiral arms produce a much greater vertical effect on the clusters than the bar, both in quantity and height; this is due to the sharper concentration of the mass on the spiral arms, when compared to the bar. When a bar and spiral arms are included, spiral arms are still capable of raising an important percentage of the simulated open clusters through chaotic diffusion (as tested from classification analysis of the resultant high-z orbits), but the bar seems to restrain them, diminishing the elevation above the plane by a factor of about two.

6 pages, 5 figures. Accepted for publication in ApJ Letters

References in corpus (2)

• The orbits of open clusters in the Galaxy
• Two Populations of Open Star Clusters in the Galaxy

Cited by in corpus (13)

• A Gaia DR2 view of the Open Cluster population in the Milky Way
• Clusters and mirages: cataloguing stellar aggregates in the Milky Way
• The Gaia-ESO Survey: Probes of the inner disk abundance gradient
• Star Clusters in Evolving Galaxies
• Discovery and astrophysical properties of Galactic open clusters in dense stellar fields using Gaia DR2
• The GALAH Survey and Gaia DR2: (Non)existence of five sparse high-latitude open clusters
• Abundances and kinematics for ten anticentre open clusters
• Modelling resonances and orbital chaos in disk galaxies. Application to a Milky Way spiral model
• On the Survival of High-Altitude Open Clusters within the Milky Way Galaxy Tides
• $\text{Siriusly}$, a newly identified intermediate-age Milky Way stellar cluster: A spectroscopic study of $\text{Gaia}$ 1
• Dynamics of thick, open spirals in Perlas potentials
• Orbit classification in a disk galaxy model with a pseudo-Newtonian central black hole
• An origin of narrow extended structure in the interstellar medium: an interstellar contrail created by a fast-moving massive object