Young Nearby Loose Associations

TL;DR

This paper identifies and characterizes nine new loose young stellar associations in the solar neighborhood, using X-ray emission and proper motion data, providing valuable targets for planetary formation studies.

Contribution

It defines and catalogs nine new young stellar associations outside the well-known Oph-Sco-Cen complex, based on systematic analysis of X-ray sources and proper motions.

Findings

Identification of nine new young stellar associations.

Members are suitable for planetary system formation studies.

Ongoing searches for low-mass and brown dwarf companions.

Abstract

A significant population of stars with ages younger than the Pleiades exists in the solar neighborhood. They are grouped in loose young associations, sharing similar kinematical and physical properties, but, due to their vicinity to the Sun, they are dispersed in the sky, and hard to identify. Their strong stellar coronal activity, causing enhanced X-ray emission, allows them to be identified as counterparts of X-ray sources. The analysis presented here is based mainly on the SACY project, aimed to survey in a systematic way counterparts of ROSAT all-sky X-ray sources in the Southern Hemisphere for which proper motions are known. We give the definition, main properties, and lists of high-probability members of nine confirmed loose young associations that do not belong directly to the well-known Oph-Sco-Cen complex. The youth and vicinity of many members of these new associations make them ideal targets for follow-up studies, specifically geared towards the understanding of planetary system formation. Searches for very low-mass and brown dwarf companions are ongoing, and it will be promising to search for planetary companions with next generation instruments.