Fractional linear polarization Q/I profiles of Mg I b triplet close to solar limb (μ = 0.1) in absence of magnetic field. The dashed lines were measured by Stenflo et al. (2000). The solid lines show the theoretical profiles obtained with the anisotropy factor ω₁ = 0.131, ω₂ = 0.0575, and ω₃ = 0.0156 for the triplet, respectively. The continuum intensity corresponds to .