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

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 $74\times 38\times 32$~pc${}^3$, while the faintest cluster members define a more elongated structure with dimensions of $98\times 24\times 18$~pc${}^3$. We suggest that the different properties of both populations is an imprint of the star formation history in this region.

arXiv comment5 pages, 1 figure, MNRAS letters (in press)

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