http://arxiv.org/abs/2205.01735
The improved astrometry precision of Gaia-eDR3 allows us to perform a detailed study of the Upper Scorpius OB association and revisit its kinematic, spatial, and age substructure. We achieve this by combining the Convergent Point method with clustering techniques, complementing with age estimations based on Gaia photometry. We obtain a set of 4028 candidate members for Upper Scorpius with completeness $\sim$99\% and contamination $\sim$11\%, extending the current census with Gaia by at least $\sim$9\%. We extract an astrometrically clean sample of 3114 sources with contamination $\sim$6\%. We show that Upper Scorpius can be divided into at least 3 main kinematic groups. We systematically investigate and characterize the Upper Scorpius’ internal structure, revealing that at least $\sim 34\%$ of its stellar populations are contained in 7 spatial substructures, with well defined boundaries, kinematics and relative ages, with suggested names: $\pi$ Scorpii (20 $^{\pm2}{\pm1}$ Myr), $\alpha$ Scorpii (14$^{\pm2}{\pm1}$ Myr), $\delta$ Scorpii (9$^{\pm2}{\pm1}$ Myr), $\beta$ Scorpii (8$^{\pm1}{\pm1}$ Myr), $\omega$ Scorpii (8$^{\pm1}{\pm1}$ Myr), $\nu$ Scorpii (7$^{\pm1}{\pm1}$ Myr), after their brightest member, and the well known $\rho$ Ophiuchi (4$^{\pm1}_{\pm1}$ Myr). We find a clear correlation in (1) density-age suggesting that these substructures are expanding at a measurable rate, and (2) tangential velocity-age, providing constrains on the dynamics of these substructures, and the position of potential past triggering events. We estimate the time at which 4 potential supernovae events occurred in Upper Scorpius. Based on these findings, we suggest a star formation scenario for Upper Scorpius with unprecedented temporal resolution.
G. Briceño-Morales and J. Chanamé
Thu, 5 May 22
8/51
Comments: N/A