N-105 IN THE LARGE-MAGELLANIC-CLOUD - A NEWLY EVOLVED H-II COMPLEX

The detailed radial velocity field of the HII region N 105, in the Lar ge Magellanic Cloud, has been obtained for the H alpha and [O III]5007 lines with a spatial sampling of 9'' and spectral ones of 16 and 7 km s(-1) respectively. The line profiles present complex splitting and b roadening in several places. The peculiar velocity field and morpholog y indicate that N 105 contains four bubble shaped nebulae, and two bri ght distinct quasi spherical HII regions, more or less coeval, embedde d inside another large shell nebula. They are formed essentially by th e action of the stellar winds of a few exciting stars, born deep insid e their parental cloud. This result is deduced from the energy added t o the ionized gas by the stellar winds of early type stars and from dy namical simulations combining the effects of stellar winds with those of high density gradients inside the neutral gas. The size and the mor phology of the HII region are conditioned by the depth inside the nata l cloud; the observed dynamic evolution of the H II region starts at t he moment of blow out of the molecular cloud. The kinematics agrees wi th the expected results from the stellar content and from the molecula r studies. The positions of masers and of an infra-red (IR) source ins ide N 105 and the structure of this nebula suggest that such an IR sou rce may be the consequence of star formation triggered by the surround ing wind pressure due to the progenitors of the presently evolved star s.