  A low mass, large core radius, and strong tidal tails suggest that the
globular cluster Palomar 5 has lost a large fraction of its initial mass over
time. If the dynamical evolution of Palomar 5 has been dominated by the effects
of mass loss, then the luminosity function should be deficient in low-mass
stars. Using deep WFPC2 F555W and F814W photometry, we determine the main
sequence luminosity functions both near the cluster center and in a field near
the half-light radius. There is no compelling evidence for mass segregation
within the cluster, but a comparison of the global mass function of Palomar 5
with those of Omega Cen and M55 indicates an increasing deficiency of stars
with progressively lower masses. A fit of the observed luminosity function to
theoretical models yields a power-law mass function with an exponent of -0.5.
The flatness of the mass function is consistent with models of the dynamical
evolution of globular clusters that have lost on the order of 90% of their
original stellar mass. We suggest that Palomar 5 has lost a large percentage of
its original stellar content as a result of tidal shocking.

Astrophysics