Stellar feedback is driving sequential star formation in the Sco-Cen OB association
We investigate the kinematics and star formation history of Scorpius-Centaurus (Sco-Cen), the nearest OB association to Earth, using Gaia DR3, APOGEE-2 DR17, and GALAH DR3 data. We focus on the sequentially aligned chains of clusters within Sco-Cen, including the Corona Australis (CrA), Lower Centaurus Crux (LCC), and Upper Scorpius (Upper Sco) chains. Our study reveals that all three cluster chains exhibit distinct patterns in 3D spatial alignment, ages, relative velocities, and masses. We propose a scenario where stellar feedback from the most massive star formation episode 15 Myr ago initiated the formation of these spatio-temporal cluster sequences. Their well-defined physical properties can be explained by their progenitor molecular clouds being continuously affected by feedback over 5–10 Myr. Approximately 40% of the stellar population in Sco-Cen formed through triggered star formation, with 35% forming along the three observed cluster chains. We propose that cluster chains are common structures in OB associations like Sco-Cen. Finally, we can isolate the feedback-induced acceleration of the CrA molecular cloud beyond the acceleration caused by the Galactic gravitational potential. This represents a first data-based measurement of molecular cloud acceleration driven by stellar feedback. Our results show the significant impact of stellar feedback on the spatial distribution and kinematics of OB associations like Sco-Cen.
