Jeans Instability of Palomar 5's Tidal Tail

Understand

Tidal tails composed of stars should be unstable to the Jeans instability and this can cause them to look like beads on a string.

• The Jeans wavelength and tail diameter determine the wavelength and growth rate of the fastest growing unstable mode.
• Consequently the distance along the tail to the first clump and spacing between clumps can be used to estimate the mass density in the tail and its longitudinal velocity dispersion.
• Clumps in the tidal tails of the globular cluster Palomar 5 could be due to Jeans instability.