Pre-main sequence population of Sco-Cen unveiled with Gaia DR2

TL;DR

This study uses Gaia DR2 data to identify and analyze the pre-main sequence stellar population in the Sco-Cen region, revealing detailed spatial distributions and new stellar groupings.

Contribution

It provides a comprehensive catalog of pre-main sequence stars in Sco-Cen using Gaia DR2, highlighting spatial structures and identifying new stellar populations.

Findings

Identified 14,459 young stellar objects in Sco-Cen.

Mapped clear concentrations of young stars, including Upper Scorpius and IC 2602.

Detected a new stellar population at ~180 pc distance.

Abstract

We use Gaia DR2 data to isolate the pre-main sequence population corresponding to the Scorpius-Lupus-Centaurus-Crux area on the sky making use the Hertzsprung-Russell diagram. A sample of $120\,911$ sources was selected with galactic coordinates $285^\circ\leq\ell\leq360^\circ$ and $-10^\circ\leq b\leq+32^\circ$, and parallaxes between $5$ and $12$~mas where the relative uncertainty in parallax was restricted to be $<10\%$. The pre-main sequence sources were isolated due to a clear separation between the pre-main and main sequences, well above the expected $0.75$ magnitude from a possible observed population of equal mass binaries. The final sample contains $14\,459$ young stellar objects. The traditional boundaries of the Sco OB2 association are well traced by clear concentrations of young stars where the Upper Scorpius region stands out as the densest concentration. The IC 2602 cluster is visible naturally near $(\ell,b)=(290^\circ,-5^\circ)$. An additional population located at ($b\sim5^\circ$ and $\ell\sim345^\circ$) with a mean distance of $\sim180\mathrm{pc}$ ($5$-$6$~mas) is observed. This is consistent with previous studies reported in the literature.