A Measurement of Diffusion in 47 Tucanae

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 $κ\approx 10-13$ arcsecond$^2$ Myr$^{-1}$ is consistent with theoretical estimates of the relaxation time in the core of 47 Tucanae of about 70 Myr.

12 pages, 10 figures, accept for publication in the Astrophysical Journal (added a short passage on blue stragglers descendants and corrected a minor typographical error in Eq. 15)