Work

The velocity field of the Scorpius-Centaurus OB association

Year: 2025

Type: article

Abstract: We present a nonparametric reconstruction of the three-dimensional velocity field of the Scorpius-Centaurus OB association (Sco-Cen). Using Gaia DR3 astrometry and radial velocities, we inferred the velocity field using information field theory on a 70 × 70 × 50 grid at a 3 pc resolution. Our model suggests the existence of a primary stellar velocity field with a secondary field that accounts for an additional young kinematic component in Upper Scorpius and Lupus. We find clear tracers of a feedback-driven expansion of the association, while Galactic rotation appears to play a subordinate role. The results confirm the existence of cluster chains and reveal coherent large-scale expansion with characteristic speeds of 1–2 km s −1 and local maxima of about 10 km s −1 . Power spectra indicate an excess of small-scale structure and slopes shallower than Kolmogorov, consistent with energy injection from stellar feedback. Maps of the divergence reveal net positive values, implying an approximate dispersal timescale of 10–15 Myr. A comparison with molecular gas in Lupus and Ophiuchus shows broadly consistent patterns but systematic velocity offsets of several km s −1 , suggesting partial decoupling for optically visible young stars and gas. The framework presented provides a physically motivated description of the Sco-Cen velocity field and a basis for quantifying the dynamical state and feedback history of OB associations in the local Galaxy.

Source: Astronomy and Astrophysics

DOI: 10.1051/0004-6361/202557273