|Abundance Trends in the Inner and Outer Galactic Disk
|458, Galactic Archaeology: Near-Field Cosmology and the Formation of the Milky Way
|Bensby, T.; Alves-Brito, A.; Oey, M. S.; Yong, D.; Meléndez, J.
|Based on high-resolution spectra obtained with the MIKE spectrograph
on the Magellan telescopes we present detailed elemental abundances
for 64 red giant stars in the inner and outer Galactic disk.
For the inner disk sample
(4–7 kpc from the Galactic centre) we find that stars
with both thin and thick disk abundance patterns are present
while for Galactocentric distances beyond 10 kpc,
we only find chemical patterns associated with the local thin disk, even for
stars far above the Galactic plane. Our results show that the relative densities
of the thick and thin disks are dramatically different from the solar
we therefore suggest that the radial scale length of the thick disk is
much shorter than that of the thin disk. A thick disk scale-length of
Lthick= 2.0 kpc, and Lthin= 3.8 kpc for the thin disk, better
match the data.