Kinematics of the Scorpius-Centaurus OB Association

TL;DR

This study reveals the detailed kinematic structure of the Scorpius-Centaurus OB association, identifying its expansion and motion characteristics through UV-velocity analysis, and estimates its expansion age.

Contribution

It introduces a new method for analyzing stellar UV velocities to identify structural components and provides the first detailed kinematic analysis of the Scorpius-Centaurus association.

Findings

The association exhibits a significant expansion with an angular velocity of 46±8 km/s/kpc.

The estimated expansion age of the complex is approximately 21±4 million years.

The complex's proper rotation velocity is lower and less reliably determined.

Abstract

A fine structure related to the kinematic peculiarities of three components of the Scorpius-Centaurus association (LCC, UCL, and US) has been revealed in the UV-velocity distribution of Gould Belt stars. We have been able to identify the most likely members of these groups by applying the method of analyzing the two-dimensional probability density function of stellar UV velocities that we developed. A kinematic analysis of the identified structural components has shown that, in general, the center--of--mass motion of the LCC, UCL, and US groups follows the motion characteristic of the Gould Belt, notably its expansion. The entire Scorpius-Centaurus complex is shown to possess a proper expansion with an angular velocity parameter of 46+-8 km/s/kpc for the kinematic center with lo=-40 degrees and Ro=110 pc found. Based on this velocity, we have estimated the characteristic expansion time of the complex to be 21+-4 Myr. The proper rotation velocity of the Scorpius-Centaurus complex is lower in magnitude, is determined less reliably, and depends markedly on the data quality.