Toward the general RGB slope-metallicity-age calibration: I
  Metallicities, Ages and Kinematics for Eight LMC Clusters
  In this paper, we discuss the properties of CMDs, age, metallicity and radial
velocities of eight massive LMC clusters using data taken from FORS2
multiobject spectrograph at the 8.2-meter VLT/UT1. The strong near-infrared Ca
II triplet (CaT) lines of RGB stars obtained from the high S/N spectra are used
to determine the metallicity and radial velocity of cluster members. We report
for the first time spectroscopically determined metallicity values for four
clusters based on the mean [Fe/H] value of ~10 cluster members each. We found
two concentrations in the distribution of ages of the target clusters. Six have
ages between 0.8-2.2 Gyr and the other two, NGC 1754 and NGC 1786, are very
old. The metallicity of the six intermediate age clusters, with a mean age of
1.5 Gyr, is -0.49 with a scatter of only 0.04. This tight distribution suggests
that a close encounter between the LMC and SMC may have caused not only the
restart of cluster formation in the LMC but the generation of the central bar.
The metallicity for the two old clusters is similar to that of the other old,
metal-poor LMC clusters. We find that the LMC cluster system exhibits disk-like
rotation with no clusters appearing to have halo kinematics and there is no
evidence of a metallicity gradient in the LMC, in contrast with the stellar
population of the MW and M33, where the metallicity decreases as galactocentric
distance increases. The LMC's stellar bar may be the factor responsible for the
dilution of any kind of gradient in the LMC.
