2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/115945We present new atmosphere models for Wolf-Rayet stars that include a self-consistent solution of the wind hydrodynamics. We demonstrate that the formation of optically thick WR winds can be explained by radiative driving on Fe line opacities, implying a strong dependence on metallicity (Z). Z-dependent model calculations for late-type WN stars show that these objects are very massive stars close to the Eddington limit, and that their formation is strongly favored for high metallicity environments.4 pages, 3 figures, to appear in proc "Metal Rich Universe" (ed. G. Israelian). CUP style file includedAstrophysicstext