a) Size of the stellar wind radio-emitting region as a function of frequency for a range of stellar mass-loss rates: 3 × 10^-12M_⊙ yr^-1 to 3 × 10^-9M_⊙ yr^-1 from bottom to top solid lines. The dotted line indicates the orbital radius of V830 Tau b. b) The same as in a), but for the flux density of the emitting wind, S_ν. Circles are the upper limits for the radio emission of V830 Tau b as presented by Bower et al. (2016).