SIMBAD references

Five LMC stellar groups of stellar associations around LH 15, 47, 52, 83, 91 have been examined in order to define their boundaries, their stellar content and their dynamical behaviour. Spectral classification of individual stars from objective prism spectra and star count in direct plates taken with the 1.2m U.K. Schmidt Telescope in Australia have provided the observational material for this investigation. Isodensity contour maps and the distribution of spectral types reveals 15 associations (some are newly detected) that contain sometimes apart from the OB type stars, faint A type stars and late type supergiants giving evidence for a continuous star formation. Their central mass density indicates that all of them are unbound systems with disruption times not longer than their age derived from their stellar population's evolutionary stage.