Based on imaging and spectroscopy obtained at the ESO NTT telescope and using an efficient image analysis algorithm , we study the core of the LMC OB association LH 13 , particularly the two compact stellar clusters Sk–66 ^ { \circ } 41 and HNT in the H ii region N 11C .
We resolve Sk–66 ^ { \circ } 41 into 15 components and for the first time the HNT cluster into 70 stars , and derive photometry for the members .
Moreover , from medium resolution spectroscopy we determine the spectral types for sixteen stars in N 11C .
We compare the color-magnitude diagrams of the clusters with that of the field stars and discuss the cluster ages .
With an age of \sim 100 Myr , the HNT cluster appears significantly older than the very young ( \leq 5 Myr ) Sk–66 ^ { \circ } 41 starburst .
We suggest that most of the ‘ field ’ O-stars in the core of N 11C have actually been ejected from Sk–66 ^ { \circ } 41 through dynamical interactions in the compact cluster .
The properties of the Sk–66 ^ { \circ } 41 and HNT clusters suggest that we are viewing different star formation regions lying at different distances along the same line of sight .