English

The velocity field of the Scorpius-Centaurus OB association

Astrophysics of Galaxies 2025-11-27 v2

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 s1^{-1} and local maxima of about 10 km s1^{-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 s1^{-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.

Keywords

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