The velocity field of the Scorpius-Centaurus OB association
Abstract
We present a non-parametric reconstruction of the three-dimensional velocity field of the Scorpius-Centaurus OB association (Sco- Cen). Using Gaia DR3 astrometry and radial velocities, we infer the velocity field using information field theory on a 70 x 70 x 50 grid at 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 and local maxima of about 10 km s. 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, 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.
Cite
@article{arxiv.2509.13607,
title = {The velocity field of the Scorpius-Centaurus OB association},
author = {S. Hutschenreuter and J. Alves and L. Posch and J. Großschedl and M. Piecka and N. Miret-Roig and S. Ratzenböck and C. Swiggum},
journal= {arXiv preprint arXiv:2509.13607},
year = {2025}
}
Comments
12 + 6 pages, accepted in Astronomy and Astrophysics, maps at https://zenodo.org/records/17107581