Clumping in hot-star winds as function of metallicity: first theoretical predictions and implications for mass-loss diagnostics

Abstract

We explore the impact of metal content on clumping in the winds of massive stars. Using numerical hydrodynamics with radiative cooling, limb darkening, and base perturbations, we simulate a wind with a fixed stellar mass and luminosity and vary the wind strength \(\bar{Q}\), which varies directly with metal content. Analysis of the radial distribution of clumping in these simulations shows that the clumping factor varies with metallicity as \(f_{cl} \simeq Z^{0.3}\), implying that observationally determined H alpha mass loss diagnostics that assume metallicity-independent clumping have overestimated by 20-30% the exponent of the mass loss rate to metallicity power law relationship.