Galactic Pal-eontology: Abundance Analysis of the Disrupting Globular
  Cluster Palomar 5
  We present a chemical abundance analysis of the tidally disrupted globular
cluster (GC) Palomar 5. By co-adding high-resolution spectra of 15 member stars
from the cluster's main body, taken at low signal-to-noise with the Keck/HIRES
spectrograph, we were able to measure integrated abundance ratios of 24 species
of 20 elements including all major nucleosynthetic channels (namely the light
element Na; $\alpha$-elements Mg, Si, Ca, Ti; Fe-peak and heavy elements Sc, V,
Cr, Mn, Co, Ni, Cu, Zn; and the neutron-capture elements Y, Zr, Ba, La, Nd, Sm,
Eu). The mean metallicity of $-1.56\pm0.02\pm0.06$ dex (statistical and
systematic errors) agrees well with the values from individual, low-resolution
measurements of individual stars, but it is lower than previous high-resolution
results of a small number of stars in the literature. Comparison with Galactic
halo stars and other disrupted and unperturbed GCs renders Pal~5 a typical
representative of the Milky Way halo population, as has been noted before,
emphasizing that the early chemical evolution of such clusters is decoupled
from their later dynamical history. We also performed a test as to the
detectability of light element variations in this co-added abundance analysis
technique and found that this approach is not sensitive even in the presence of
a broad range in sodium of $\sim$0.6 dex, a value typically found in the old
halo GCs. Thus, while methods of determining the global abundance patterns of
such objects are well suited to study their overall enrichment histories,
chemical distinctions of their multiple stellar populations is still best
obtained from measurements of individual stars.
