The Galactic Bulge

The boxy Galactic Bulge is believed to have formed long ago through a
bar-forming and bar-buckling instability of the Galactic disk.  In
order to study the chemical and dynamical properties of this bulge, we
have acquired spectra of 28,000 red giant candidate stars towards the
bulge, and I will describe the outcome of this large survey (the ARGOS
survey).  We are able to estimate the distances for all of these
stars, and remove several thousand stars which lie in the foreground
or background of the bulge.

The chemical properties of the bulge stars show that the bulge-forming
instability moved stars from the early thin and thick disk into the
bulge.  These stars are now locked into the bulge as chemically
identifiable fossils of the early disks. We are not able to put useful
limits on the presence of an additional classical (merger-related)
bulge component in the inner Galaxy, but our kinematical data are
fully consistent with the predictions of the instability formation
scenario.