The chemistry of stars in the bar of the Milky Way
  We use a sample of 938 red clump giant stars located in the direction of the
galactic long bar to study the chemistry of Milky Way bar stars. Kinematically
separating stars on bar orbits from stars with inner disc orbits, we find that
stars on bar-like orbits are more metal rich with a mean iron abundance of
<[Fe/H]>=+0.30 compared to <[Fe/H]>=+0.03 for the inner disc. Spatially
selecting bar stars is complicated by a strong vertical metallicity gradient of
-1.1dex/kpc, but we find the metallicity distribution varies in a manner
consistent with our orbital selection. Our results have two possible
interpretations. The first is that the most metal rich stars in the inner
Galaxy pre-existed the bar, but were kinematically cold at the time of bar
formation and therefore more easily captured onto bar orbits when the bar
formed. The second is that the most metal rich stars formed after the bar,
either directly onto the bar following orbits or were captured by the bar after
their formation.
