Verification of stellar R_birth for two different subsamples. Top: distribution of R_birth of stars in mono-age populations currently located in the solar neighbourhood (|z| < 1.5 kpc; |R − 8.125| < 0.15 kpc) with eccentricity <0.5. Older stars in the solar neighbourhood originate in the inner disc while younger populations are born locally, in agreement with expectations. Bottom: stellar mass distribution in the R–R_birth (i.e. current–birth) plane for stars with age <4 Gyr, showing overall minimal net migration in the most recent gigayears. The colour scale represents the globally normalised, mass-weighted probability density of stars.