A Measurement of Diffusion in 47 Tucanae

TL;DR

This study directly measures the diffusion rate of stars in the core of 47 Tucanae using Hubble data, confirming theoretical predictions of gravitational relaxation times in a globular cluster.

Contribution

First direct measurement of stellar diffusion due to gravitational relaxation in a globular cluster core.

Findings

Diffusion rate κ ≈ 10-13 arcsecond² Myr⁻¹

Measured relaxation time ~70 Myr

Results align with theoretical estimates

Abstract

Using images from the Hubble Space Telescope Wide-Field Camera 3, we measure the rate of diffusion of stars through the core of the globular cluster 47 Tucanae using a sample of young white dwarfs identified in these observations. This is the first direct measurement of diffusion due to gravitational relaxation. We find that the diffusion rate $\kappa\approx 10-13$ arcsecond$^2$ Myr$^{-1}$ is consistent with theoretical estimates of the relaxation time in the core of 47 Tucanae of about 70 Myr.