Based on imaging and spectroscopy obtained at the ESO NTT telescope and usi
ng an efficient image analysis algorithm, we study the core of the LMC OB a
ssociation LH 13, particularly the two compact stellar clusters Sk-66 degre
es 41 and HNT in the HII region N 11C. We resolve Sk-66 degrees 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 d
iscuss the cluster ages. With an age of similar to 100 Myr, the HNT cluster
appears significantly older than the very young (less than or equal to 5 M
yr) Sk-66 degrees 41 starburst. We suggest that most of the 'field' O-stars
in the core of N 11C have actually been ejected from Sk-66 degrees 41 thro
ugh dynamical interactions in the compact cluster. The properties of the Sk
-66 degrees 41 and HNT clusters suggest that we are viewing different star
formation regions lying at different distances along the same line of sight
.