Wind properties of Milky Way and SMC massive stars: empirical <i>Z</i> dependence from <scp>cmfgen</scp> models

Detailed knowledge about stellar winds and evolution at different metallicities is crucial for understanding populations feedback in the Local Group of galaxies beyond. Despite efforts literature, we still lack a comprehensive, empirical view dependence wind properties on metallicity ($Z$). Here, investigate O B stars Milky Way (MW) Small Magellanic Cloud (SMC). We gathered sample 96 analyzed by means NLTE code CMFGEN. explored their strengths terminal velocities to address $Z$ dependence, over large luminosity range. The wind-luminosity relation (WLR) obtained updates extends previous results literature. It reveals agreement with radiatively driven theory. For bright objects ($\log L/L_\odot \gtrsim 5.4$), infer that $\dot{M} \sim Z^{0.5-0.8}$. However, this seems get weaker or vanish lower luminosities. analysis suggests shallow $Z^n$ $n 0.1-0.2$, but it should be confirmed larger more accurate $V_{\infty}$ determinations. Recent SMC based PoWR support our inferred WLR. On other hand, recent bow-shocks measurements stand mostly above derived Theoretical calculations WLR are not precise, specially low $L$, where scatter. Deviations between predictions identified due weak problem extreme predicted models. Z suggested deserves further investigations, given its astrophysical implications.