We report new spectroscopic observations obtained with the Michigan/ Magellan Fiber System of 308 red giants ( RGs ) located in two fields near the photometric center of the bar of the Large Magellanic Cloud .
This sample consists of 131 stars observed in previous studies ( in one field ) and 177 newly-observed stars ( in the second field ) selected specifically to more reliably establish the metallicity and age distributions of the bar .
For each star , we measure its heliocentric line-of-sight velocity , surface gravity and metallicity from its high-resolution spectrum ( effective temperatures come from photometric colors ) .
The spectroscopic Hertzsprung-Russell diagrams—modulo small offsets in surface gravities—reveal good agreement with model isochrones .
The mean metallicity of the 177-RG sample is [ Fe / H ] = -0.76 \pm 0.02 with a metallicity dispersion \sigma = 0.28 \pm 0.03 .
The corresponding metallicity distribution—corrected for selection effects—is well fitted by two Gaussian components : one metal-rich with a mean -0.66 \pm 0.02 and a standard deviation 0.17 \pm 0.01 , and the other metal-poor with -1.20 \pm 0.24 and 0.41 \pm 0.06 .
The metal-rich and metal-poor populations contain approximately 85 % and 15 % of stars , respectively .
We also confirm the velocity dispersion in the bar center decreases significantly from 31.2 \pm 4.3 to 18.7 \pm 1.9 km s ^ { -1 } with increasing metallicity over the range -2.09 to -0.38 .
Individual stellar masses are estimated using the spectroscopic surface gravities and the known luminosities .
We find that lower mass hence older RGs have larger metallicity dispersion and lower mean metallicity than the higher-mass , younger RGs .
The estimated masses , however , extend to implausibly low values ( \sim 0.1 ~ { } M _ { \odot } ) making it impossible to obtain an absolute age-metallicity or age distribution of the bar .