Skip to main content

Research Repository

Advanced Search

The Kinematics of the Scorpius-Centaurus OB Association from Gaia DR1

Wright

The Kinematics of the Scorpius-Centaurus OB Association from Gaia DR1 Thumbnail


Authors



Abstract

We present a kinematic study of the Scorpius-Centaurus (Sco-Cen) OB association (Sco OB2) using Gaia DR1 parallaxes and proper motions. Our goal is to test the classical theory that OB associations are the expanded remnants of dense and compact star clusters disrupted by processes such as residual gas expulsion. Gaia astrometry is available for 258 out of 433 members of the association, with revised Hipparcos astrometry used for the remainder. We use this data to confirm that the three subgroups of Sco-Cen are gravitationally unbound and have non-isotropic velocity dispersions, suggesting they have not had time to dynamically relax. We also explore the internal kinematics of the subgroups to search for evidence of expansion. We test Blaauw’s classical linear model of expansion, search for velocity trends along the Galactic axes, compare the expanding and non-expanding convergence points, perform traceback analysis assuming both linear trajectories and using an epicycle approximation, and assess the evidence for expansion in proper motions corrected for virtual expansion / contraction. None of these methods provide coherent evidence for expansion of the subgroups, with no evidence to suggest that the subgroups had a more compact configuration in the past. We find evidence for kinematic substructure within the subgroups that supports the view that they were not formed by the disruption of individual star clusters. We conclude that Sco-Cen was likely born highly substructured, with multiple small-scale star formation events contributing to the overall OB association, and not as single, monolithic bursts of clustered star formation.

Acceptance Date Jan 29, 2018
Publication Date May 1, 2018
Publicly Available Date Mar 29, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Publisher Oxford University Press
Pages 381-398
DOI https://doi.org/10.1093/mnras/sty207
Keywords stars, formation, kinematics and dynamics, open clusters and associations, individual, Scorpius-Centaurus, Sco OB2, Upper Scorpius, Upper Centaurus-Lupus, Lower Centaurus-Crux
Publisher URL http://doi.org/10.1093/mnras/sty207

Files




You might also like



Downloadable Citations