Near-IR trigonometric parallaxes of nearby stars in the Galactic plane using the VVV

TL;DR

This study demonstrates the VVV survey's ability to measure high-precision parallaxes for very low mass stars in the Galactic plane, revealing their distances, binary status, and Galactic population membership.

Contribution

First-time precise parallaxes for high proper motion stars using VVV, extending distance measurements for very low mass stars beyond previous ground-based surveys.

Findings

Measured parallaxes for 18 stars with milli-arcsecond precision.

Identified 5 likely halo low-mass stars based on velocities.

Detected 4 nearby objects likely belonging to the thick disk.

Abstract

We use the multi-epoch K$\rm _S$ band observations, covering a $\sim$5 years baseline to obtain milli and sub-milli arcsec precision astrometry for a sample of eighteen previously known high proper motion sources, including precise parallaxes for these sources for the first time. In this study we show the capability of the VVV project to measure high precision trigonometric parallaxes for very low mass stars (VLMS) up to distances of $\sim$250\,pc reaching farther than most other ground based surveys or space missions for these types of stars. Additionally, we used spectral energy distribution to search for evidence of unresolved binary systems and cool sub-dwarfs. We detected five systems that are most likely VLMS belonging to the Galactic halo based on their tangential velocities, and four objects within 60 pc that are likely members of the thick disk. A more comprehensive study of high proper motion sources and parallaxes of VLMS and brown dwarfs with the VVV is ongoing , including thousands of newly discovered objects.