Galaxy Genesis -- unravelling the epoch of dissipation in the early disk

Abstract

So how did the Galactic disk form and can the sequence of events ever be unravelled from the vast stellar inventory? This will require that some of the residual inhomogeneities from prehistory escaped the dissipative process at an early stage. Fossil hunting to date has concentrated mostly on the stellar halo, but a key source of information will be the thick disk. This is believed to be a 'snap frozen' relic which formed during or shortly after the last major epoch of dissipation, or it may have formed from infalling systems early in the life of the Galaxy. As part of the KAOS Galaxy Genesis project, we explore the early history of the halo and the thick disk by looking for discrete substructures, either due to infall or in situ star formation, through chemical tagging. This will require high signal to noise, echelle spectroscopy of up to a million stars throughout the disk. Our program has a short-term and a long-term goal.