We have obtained near-infrared spectra covering the Ca ii triplet lines for a large number of stars associated with 16 SMC clusters using the VLT + FORS2 .
These data compose the largest available sample of SMC clusters with spectroscopically derived abundances and velocities .
Our clusters span a wide range of ages and provide good areal coverage of the galaxy .
Cluster members are selected using a combination of their positions relative to the cluster center as well as their location in the CMD , abundances and radial velocities .
We determine mean cluster velocities to typically 2.7 km s ^ { -1 } and metallicities to 0.05 dex ( random errors ) , from an average of 6.4 members per cluster .
By combining our clusters with previously published results , we compile a sample of 25 clusters on a homogenous metallicity scale and with relatively small metalliciy errors , and thereby investigate the metallicity distribution , metallicity gradient and age-metallicity relation ( AMR ) of the SMC cluster system .
For all 25 clusters in our expanded sample , the mean metallicity [ Fe/H ] = - 0.96 with \sigma = 0.19 .
The metallicity distribution may possibly be bimodal , with peaks at \sim - 0.9 dex and - 1.15 dex .
Similar to the LMC , the SMC cluster system gives no indication of a radial metallicity gradient .
However , intermediate-age SMC clusters are both significantly more metal-poor and have a larger metallicity spread than their LMC counterparts .
Our AMR shows evidence for 3 phases : a very early ( > 11 Gyr ) phase in which the metallicity reached \sim - 1.2 dex , a long intermediate phase from \sim 10 - 3 Gyr in which the metallicity only slightly increased , and a final phase from 3 - 1 Gyr ago in which the rate of enrichment was substantially faster .
We find good overall agreement with the model of Pagel & Tautvaišienė ( 55 ) , which assumes a burst of star formation at 4 Gyr .
Finally , we find that the mean radial velocity of the cluster system is 148 km s ^ { -1 } , with a velocity dispersion of 23.6 km s ^ { -1 } and no obvious signs of rotation amongst the clusters .
Our result is similar to what has been found from a wide variety of kinematic tracers in the SMC , and shows that the SMC is best represented as a pressure supported system .