Characterization of the Helmi streams as detected by the single-linkage algorithm. Left: distribution of the 51 671 stars analysed in this work as well as clusters 60 and 61 (Helmi streams) in the E − L_z space. Middle: colour absolute magnitude diagram for clusters 60 and 61. We overlay isochrones of a 10.4 Gyr ([Fe/H] = −0.91) and a 13.4 Gyr ([Fe/H] = −2.21) old populations from the updated BaSTI stellar evolution models (Hidalgo et al. 2018) in the Gaia EDR3 photometric system. Right: metallicity distribution functions from LAMOST-LRS for clusters 60 and 61, where the cumulative distributions are shown in the inset.