Three-dimensional structure of the Upper Scorpius association with the Gaia first data release

TL;DR

This study uses Gaia data and proper motion analysis to map the 3D structure of the Upper Scorpius association, revealing a prolate ellipsoid shape and differences between bright and faint star populations.

Contribution

It provides a detailed 3D morphological analysis of Upper Scorpius using Gaia data, highlighting structural differences linked to star formation history.

Findings

Mean distance of 146 pc with uncertainties

Bright stars form a prolate ellipsoid of 74x38x32 pc

Faint stars form a more elongated structure of 98x24x18 pc

Abstract

Using new proper motion data from recently published catalogs, we revisit the membership of previously identified members of the Upper Scorpius association. We confirmed 750 of them as cluster members based on the convergent point method, compute their kinematic parallaxes and combined them with Gaia parallaxes to investigate the 3D structure and geometry of the association using a robust covariance method. We find a mean distance of $146\pm 3\pm 6$~pc and show that the morphology of the association defined by the brightest (and most massive) stars yields a prolate ellipsoid with dimensions of $74\times38\times32$~pc$^{3}$, while the faintest cluster members define a more elongated structure with dimensions of $98\times24\times18$~pc$^{3}$. We suggest that the different properties of both populations is an imprint of the star formation history in this region.