The Star Formation History of the Starburst Region NGC 2363 and its Surroundings

We present HST optical images and UV spectra, as well as ground-basednear-infrared images of the high surface brightness giant HII region NGC 2363(NGC 2366-I) and its surroundings. The massive star content of the southern endof the dwarf irregular galaxy NGC 2366 is investigated, with an emphasis onWolf-Rayet and red supergiant stars, and we attempt the reconstruction of thetime sequence of the most recent episode of massive star formation at thesouthwestern tip of the galaxy. We show that the most massive super cluster Aof NGC 2363 is still embedded in dust; from the photoevaporative erosion or``cleaning'' time scale of the associated cloud, we infer its age to be 1 Myror less. We conclude that the star-forming complex NGC 2366-I and II is a goodexample of a multiple stage starburst with a characteristic age decreasing from10 Myr to less than 1 Myr over a linear scale of 400 pc. The age sequence ofthe stars and the gas kinematics suggest that these powerful star formationepisodes are being triggered by a small passing-by satellite.