Metallicities, Age--Metallicity relationships, and Kinematics of Red
  Giant Branch Stars in the Outer Disk of the Large Magellanic Cloud
  The outer disk of the LMC is studied in order to unveil clues about its
formation and evolution. Complementing our previous studies in innermost fields
(3<R<7 kpc), we obtained deep color magnitude diagrams in 6 fields with radius
from 5.2 to 9.2 kpc. The comparison with isochrones shows that while the oldest
population is approximately coeval in all fields, the age of the youngest
populations increases with increasing radius. Low-resolution spectroscopy in
the infrared CaII triplet region has been obtained for about 150 stars near the
tip red giant branch in the same fields. Radial velocities and stellar
metallicities have been obtained from these spectra. The metallicity
distribution of each field has been analyzed together with those previously
studied. The metal content of the most metal-poor objects, which are also the
oldest according to the derived age-metallicity relationships, is similar in
all fields independently of the radius. However, while the metallicity of the
most metal-rich objects measured, which are the youngest ones, remains constant
in the inner 6 kpc, it decreases with increasing radius from there off. The
same is true for the mean metallicity. According to the derived age-metallicity
relationships, which are consistent with being the same in all fields, this
result may be interpreted as an outside-in formation scheme in opposition with
the inside-out scenario predicted by LCDM cosmology for a galaxy like the LMC.
The analysis of the radial velocities of our sample of giants shows that they
follow a rotational cold disk kinematics. The velocity dispersion increases as
metallicity decreases indicating that the most metal-poor/oldest objects are
distributed in a thicker disk than the most metal-rich/youngest ones in
agreement with the findings in other disks such as that of the Milky Way. They
do not seem to be part of a hot halo, if one exists in the LMC.
