rho Oph region revisited with Gaia EDR3

We apply a multivariate classification algorithm to this catalog to identify new, co- moving population candidates. We find 191 high-fidelity new YSO candidates in the Gaia EDR3 catalog belonging to the {rho} Oph region. The new sources appear to be mainly Class III M-stars and substellar objects and are less extincted than the known members, while we find that 28 of previously unknown sources are YSOs with circumstellar disks (Class I or Class II).

The analysis of the proper motion distribution of the entire sample reveals a well-defined bimodality, implying two distinct populations sharing a similar 3D volume. The first population comprises young stars' clusters around the {rho} Ophiuchi star and the main Ophiuchus clouds (L1688, L1689, L1709). In contrast, the second population is slightly older (~10Myr), more dispersed, has a distinct proper motion, and is possibly from the Upper-Sco group.

The two populations are moving away from each other at about 4.1km/s and will no longer overlap in about 4Myr. Finally, we flag 17 sources in the literature sample as likely impostors, which are sources that exhibit large deviations from the average properties of the {rho} Oph population. Our results show the importance of accurate 3D space and motion information for improved stellar population analysis.