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arXiv · 2509.13607

The velocity field of the Scorpius-Centaurus OB association

S. Hutschenreuter·J. Alves·L. Posch·J. Großschedl·M. Piecka·N. Miret-Roig·S. Ratzenböck·C. Swiggum
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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$^{-1}$ 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.

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S. Hutschenreuter, J. Alves, L. Posch, J. Großschedl, M. Piecka, N. Miret-Roig, S. Ratzenböck, C. Swiggum. 2025-11-26. The velocity field of the Scorpius-Centaurus OB association. https://arxiv.org/abs/2509.13607

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