Initial conditions in the evolution of OB and Wolf-Rayet stars in N 105 of the LMC

Abstract

The detailed radial velocity field of the H II region N105, in the LMC, has been obtained for the Hα and [O III] 5007 lines with a spatial sampling of 9″ and a spectral sampling of 16 and 7kms⁻¹. The peculiar velocity field and morphology indicate that N105 contains four bubble shaped nebulae and two bright distinct quasi-spherical H II regions, more or less coeval, embedded inside another large shell nebula. They are essentially formed by the action of stellar winds of a few exciting stars, born deep inside their parental cloud. This result is deduced from the energy input inside the ionized gas by the stellar winds of early type stars and from dynamical simulations combining the effects of stellar winds with those of high density gradients inside the neutral gas. The size and morphology of the H II region are conditioned by the depth inside the natal cloud; the observed dynamical time-scale of the H II region starts at the moment of blow-out of the molecular cloud.