Radial mode surface velocities (logarithmic scale) as a function of the frequency at maximum oscillation power, ν_max (logarithmic scale). The fully opaque lines represent models evaluated using Eq. (18). The semi-transparent lines show models evaluated using Eq. (5.21) from Samadi et al. (2015). The colour represent the masses of the evolutionary tracks. The black diamonds show the ground-based Doppler velocity measurements compiled by Samadi et al. (2012).