The velocity dispersion (σ) in a young stellar population is a critical parameter, since it is closely tied to the boundedness and dispersal of clusters, a process that contributes to the overall structure and evolution of the Galactic field.
With the development of a new machine-learning-based clustering tool in combination with 5D astrometric data from Gaia DR3, we were able to provide a more detailed clustering solution for the nearby OB association Scorpius-Centaurus. We find that the Sco-Cen complex has a larger extent than historically established and that it contains more than 30 individual stellar subpopulations with ages from about 2–20 Myr. This updated view now allows a more detailed examination of the formation history of this region. We identify clear spatial-temporal patterns throughout the complex, with older populations being located at the center and younger populations at the outskirts of the region.
By adding auxiliary radial velocity (RV) data, we can now study the 3D spatial dynamics of the more than 30 stellar subpopulations. We find that the whole complex is expanding on the 100-pc scale and that the motions are correlated to the clusters' ages. And, we can now investigate the evolution of velocity dispersion in 3D within a single association. We find that the velocity dispersion increases similarly as the size of the association with time (cluster age), which results in a similar correlation as the canonical Larson’s relation for molecular clouds.
The spatial-temporal patterns and dynamical analysis indicate a feedback-driven formation history, where massive stars (from the older clusters in the center) have influenced subsequent star formation, propagating from inside-out. Feedback was likely able to push the surrounding gas, changing the relative motions of the primordial (remaining) cloud(s), and eventually influenced the total velocity dispersion of the whole association, as observed today. In conclusion, our research provides a quantif
