HST observations of the LMC compact HII region N11A

We present a study of the LMC compact H II region N11A using Hubble Space Telescope imaging observations which resolve N11A and reveal its unknown nebular and stellar features. The presence of a sharp ionization front extending over more than 4" (1 pc) and fine structure filaments as well as larger loops indicate an environment typical of massive star formation regions, in agreement with high [O III]/H beta line ratios. N11A is a young region, as deduced from its morphology, reddening, and especially high local concentration of dust, as indicated by the Balmer decrement map. Our observations also reveal a cluster of stars lying towards the central part of N11A. Five of the stars are packed in an area less than 2" (0.5 pc), with the most luminous one being a mid O type star. N11A appears to be the most evolved compact Hii region in the Magellanic Clouds so far studied.