Detailed Mg I λ2852 velocity structure showing the very narrow components near 0 km s⁻¹ in the right region. The model fit (solid orange line) overlays the spectrum (black histogram) and the Voigt profiles of individual components are shown in thin blue lines, with tick marks above the spectrum indicating their centroids. In our fiducial fit shown here, the components at ≈ − 2 and 0 km s⁻¹ have best-fit b parameters of just 0.29 ± 0.07 and 0.22 ± 0.13 km s⁻¹.