Detailed Chemical Abundances of Four Stars in the Unusual Globular
  Cluster, Palomar 1
  Detailed chemical abundances for twenty one elements are presented for four
red giants in the anomalous outer halo globular cluster Palomar 1 ($R_{\rm{GC}}
= 17.2$ kpc, $Z=3.6$ kpc) using high-resolution (R=36000) spectra from the High
Dispersion Spectrograph (HDS) on the Subaru Telescope. Pal 1 has long been
considered unusual because of its low surface brightness, sparse red giant
branch, young age, and its possible association with two extragalactic streams
of stars---this paper shows that its chemistry further confirms its unusual
nature. The mean metallicity of the four stars, $[\rm{Fe/H}] = -0.60 \pm 0.01$,
is high for a globular cluster so far from the Galactic center, but is low for
a typical open cluster. The [$\alpha$/Fe] ratios, though in agreement with the
Galactic stars within the $1\sigma$ errors, agree best with the lower values in
dwarf galaxies. No signs of the Na/O anticorrelation are detected in Pal 1,
though Na appears to be marginally high in all four stars. Pal 1's neutron
capture elements are also unusual: its high [Ba/Y] ratio agrees best with dwarf
galaxies, implying an excess of second-peak over first-peak s-process elements,
while its [Eu/$\alpha$] and [Ba/Eu] ratios show that Pal 1's contributions from
the r-process must have differed in some way from normal Galactic stars.
Therefore, Pal 1 is chemically unusual, as well in its other properties. Pal 1
shares some of its unusual abundance characteristics with the young clusters
associated with the Sagittarius dwarf galaxy remnant and the intermediate-age
LMC clusters, and could be chemically associated with the Canis Majoris
overdensity; however it does not seem to be similar to the Monoceros/Galactic
Anticenter Stellar Stream.
