URAT South Parallax Results: Discovery of New Nearby Stars

TL;DR

This paper reports 916 new trigonometric parallaxes of nearby stars from the URAT survey, expanding the catalog of known nearby stars and identifying various stellar types with high accuracy.

Contribution

The study provides a large set of new parallaxes for southern hemisphere stars, improving the completeness and accuracy of nearby star catalogs.

Findings

916 new parallaxes for southern sky stars

High precision with errors between 2 and 13 mas

Expanded 25 pc sample including 729 northern parallaxes

Abstract

We present 916 trigonometric parallaxes and proper motions of newly discovered nearby stars from the United States Naval Observatory (USNO) Robotic Astrometric Telescope (URAT). Observations were taken at the Cerro Tololo Interamerican Observatory (CTIO) over a 2 year period from Oct 2015 to Oct 2017 covering the entire sky south of about +25 deg declination. SPM4 and UCAC4 early epoch catalog data were added to extend the temporal coverage for the parallax and proper motion fit up to 48 years. Using these new URAT parallaxes, optical and near-IR photometry from the APASS and 2MASS catalogs, we identify possible new nearby dwarfs, young stars, low-metallicity subdwarfs and white dwarfs. Comparison to known trigonometric parallaxes show a high quality of the URAT-based results confirming the error in parallax of the URAT south parallaxes reported here to be between 2 and 13 mas. We also include additional 729 trigonometric parallaxes from the URAT north 25 pc sample published in Finch & Zacharias (2016) here after applying the same criterion as for the southern sample to have a complete URAT 25 pc sample presented in this paper.