Chronostar – II. Kinematic age and substructure of the Scorpius–Centaurus OB2 association. Issue 3 (16th December 2022)

• Record Type: Journal Article
• Authors: Žerjal, Maruša; Ireland, Michael J; Crundall, Timothy D; Krumholz, Mark R; Rains, Adam D
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 519:Issue 3(2023)
• Page Start: 3992
• Page End: 4009
• Publication Date: 2022-12-16
• Subjects: stars: kinematics and dynamics -- Galaxy: open clusters and associations: individual: Scorpius-Centaurus association -- Galaxy: kinematics and dynamics; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stac3693
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: The nearest region of massive star formation – the Scorpius–Centaurus OB2 association (Sco–Cen) – is a local laboratory ideally suited to the study of a wide range of astrophysical phenomena. Precision astrometry from the Gaia mission has expanded the census of this region by an order of magnitude. However, Sco–Cen's vastness and complex substructure make kinematic analysis of its traditional three regions, Upper Scorpius, Upper Centaurus-Lupus, and Lower Centaurus-Crux, challenging. Here, we use chronostar, a Bayesian tool for kinematic age determination, to carry out a new kinematic decomposition of Sco–Cen using full six-dimensional kinematic data. Our model identifies eight kinematically distinct components consisting of 8185 stars distributed in dense and diffuse groups, each with an independently fit kinematic age; we verify that these kinematic estimates are consistent with isochronal ages for K dwarfs. Both Upper Centaurus-Lupus and Lower Centaurus-Crux are split into two parts. The kinematic age of the component that includes PDS 70, one of the most well-studied systems currently forming planets, is 15 ± 3 Myr.