The evolution of velocity dispersion in OB associations - The case of Sco-Cen

Josefa Grossschedl, João Alves, Sebastian Ratzenböck

Veröffentlichungen: Beitrag zu KonferenzSonstiger KonferenzbeitragPeer Reviewed

Abstract

The velocity dispersion (σ) in a young stellar population is a critical parameter, since it is closely tied to the boundedness and dispersal of clusters, a process that contributes to the overall structure and evolution of the Galactic field. Velocity dispersion in young stellar populations also offers vital clues to the processes governing star formation, dynamical evolution, and the feedback mechanisms in different star-forming environments. Therefore, understanding the evolution of velocity dispersion in the build-up of a stellar population is crucial for piecing together the larger puzzle of star formation and Galactic evolution. With the development of a new machine-learning-based clustering tool (SigMA) in combination with 5D astrometric data from Gaia DR3, we were recently able to provide a more detailed clustering solution for the nearby OB association Scorpius-Centaurus. We find that the Sco-Cen complex has a larger extent than historically established and that it contains about 34 individual stellar subpopulations with ages from about 2-20 Myr. This updated view now allows a more detailed examination of the formation history of this region. We identify clear spatial-temporal patterns throughout the complex, with older populations being located at the center and younger populations at the outskirts of the region. By adding auxiliary radial velocity (RV) data, we can study the 3D spatial dynamics of the 34 subpopulations. We find that the whole complex is expanding on the 100-pc scale and that the motions are correlated to the clusters' ages. Moreover, we can now investigate the evolution of velocity dispersion in 3D (σ_3D) within a single association; we find that the velocity dispersion monotonically increases with age when successively adding clusters* (from old to young) for the calculation of σ_3D, cumulating in about 4 km/s, while individual clusters only have velocity dispersions on the order of about 1 km/s. The spatial-temporal patterns and dynamical analysis indicate a feedback-driven formation history, where massive stars (from the older clusters in the center) influenced subsequent star formation, propagating from inside-out. Feedback was likely able to push the surrounding gas, changing the relative motions of the primordial (remaining) cloud(s), and eventually increasing to the total velocity dispersion of the whole association, as observed today. In conclusion, our research provides a quantifiable assessment of the impact of feedback from massive stars in young complexes like Sco-Cen, where we find relatively "simple" patterns of propagated star formation. (*The term cluster is used here in a statistical sense; the clusters in Sco-Cen are likely not gravitationally bound)
OriginalspracheEnglisch
PublikationsstatusVeröffentlicht - 1 Juli 2024
VeranstaltungEuropean Astronomical Society Annual Meeting 2024 - Padova Congress, Padova, Italien
Dauer: 1 Juli 20245 Juli 2024
https://eas.unige.ch/EAS2024/

Konferenz

KonferenzEuropean Astronomical Society Annual Meeting 2024
KurztitelEAS 2024
Land/GebietItalien
OrtPadova
Zeitraum1/07/245/07/24
Internetadresse

ÖFOS 2012

  • 103003 Astronomie
  • 103004 Astrophysik

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