Radial velocity profiles for the wind acceleration functions currently available in STELLAR_WIND.PY. The formulae for these functions can be found in Table 1. For the beta_law we show two curves that are good fits for hot massive stars ( β = 0.8) and cool giants ( β = 2.0) (Lamers & Cassinelli 1999). To illustrate the shape of the acceleration curves, we have chosen υ₀ = 0.2 υ_∞, r_{acc_start} = 2 R_* (for the delayed_rsquared function), and r_mid = 3 R_* and s = α = 10 (for the logistic and agb function).