Correlations between different contributions to the Hε broadening. Panel a: Width of Hε (Δλ_D^fit, from a Gaussian fit) and thermal broadening (v_th). Panel b: Nonthermal broadening (v_nth) and nonthermal velocity (ξ). Panel c: Width of Hε (Δλ_D^fit) and the opacity broadening factor (Opf). The color of the points indicates if Hε is optically thin or thick, as shown by the color bar that shows log₁₀(τ_afd). The probability density functions of the points, calculated using Gaussian kernel density estimation, are shown at the top and right of each panel. The solid lines in panels a and b denote the y = x curve.