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N 105 in the Large Magellanic Cloud: a newly evolved H II complex *
P. Ambrocio-Cruz 1, 2,
A. Laval 1,
M. Marcelin 1,
P. Amram 1 and
F. Comerón 3
Received 4 May 1998 / Accepted 26 June 1998
The detailed radial velocity field of the H II region N 105, in the Large Magellanic Cloud, has been obtained for the H and [O III ]5007 lines with a spatial sampling of and spectral ones of 16 and 7 km s-1 respectively. The line profiles present complex splitting and broadening in several places. The peculiar velocity field and morphology indicate that N 105 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 formed essentially by the action of the stellar winds of a few exciting stars, born deep inside their parental cloud. This result is deduced from the energy added to 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 the morphology of the H II region are conditioned by the depth inside the natal cloud; the observed dynamic evolution of the H II region starts at the moment of blow out of the molecular cloud.
The kinematics agrees with the expected results from the stellar content and from the molecular studies. The positions of masers and of an infra-red (IR) source inside N 105 and the structure of this nebula suggest that such an IR source may be the consequence of star formation triggered by the surrounding wind pressure due to the progenitors of the presently evolved stars.
Key words: stars: Wolf-Rayet ISM: H ii regions ISM: individual objects: N 105 (LMC) ISM: kinematics and dynamics galaxies: Magellanic Clouds
Send offprint requests to: P. Ambrocio-Cruz
Online publication: September 30, 1998