Escape velocity as a function of galactocentric distance (top). We also shown in grey the expected behaviour of the escape velocity for four often-used Milky Way models. The bottom panel shows the logarithm of the number of stars for each distance bin. The blue marker indicates the v_esc that we determined using a local sample of stars, see Sect. 5. The error bars indicate the 1σ confidence levels. We note that the local sample is not the same as the data sample at the bin of ∼8.2 kpc, therefore the two markers there do not overlap exactly.