Migration in the shearing sheet and estimates for young open cluster migration

TL;DR

This study uses N-body simulations to analyze star and cluster migration in galactic disks, linking migration distances to spiral structure properties and comparing results with observed open clusters.

Contribution

It provides new estimates for star and cluster migration distances in shearing disks, connecting simulation results with observed open cluster metallicities.

Findings

Migration distances depend on spiral structure and surface density contrast.

Observed metallicity variations are consistent with simulated migration estimates.

Surface density contrast in the solar neighborhood is higher than COBE data suggests.

Abstract

Using tracer particles embedded in self-gravitating shearing sheet N-body simulations, we investigate the distance in guiding centre radius that stars or star clusters can migrate in a few orbital periods. The standard deviations of guiding centre distributions and maximum migration distances depend on the Toomre or critical wavelength and the contrast in mass surface density caused by spiral structure. Comparison between our simulations and estimated guiding radii for a few young super-solar metallicity open clusters, including NGC 6583, suggests that the contrast in mass surface density in the solar neighbourhood has standard deviation (in the surface density distribution) divided by mean of about 1/4 and larger than measured using COBE data by Drimmel and Spergel. Our estimate is consistent with a standard deviation of $\sim$0.07 dex in the metallicities measured from high-quality spectroscopic data for 38 young open clusters (<1 Gyr) with mean galactocentric radius 7-9 kpc.