Gaia: 3-dimensional census of the Milky Way Galaxy

TL;DR

Gaia is a space-based astrometry mission providing comprehensive 3D positional and 2D velocity data for over two billion stars in the Milky Way, revolutionizing our understanding of galactic structure and dynamics.

Contribution

This paper introduces Gaia's all-sky, high-precision astrometric survey, delivering unprecedented 3D and 2D stellar data for large-scale astrophysical research.

Findings

Over two billion stars cataloged with 5-D phase space data

Radial velocities for 300 million brightest stars

Significant advancements in understanding Milky Way structure

Abstract

Astrometry from space has unique advantages over ground-based observations: the all-sky coverage, relatively stable, and temperature and gravity invariant operating environment delivers precision, accuracy and sample volume several orders of magnitude greater than ground-based results. Even more importantly, absolute astrometry is possible. The European Space Agency Cornerstone mission Gaia is delivering that promise. Gaia provides 5-D phase space measurements - 3 spatial coordinates and two space motions in the plane of the sky - for a representative sample of the Milky way's stellar populations, including over two billion stars, being about one percent of the stars over about 50 percent of the radius. Full 6-D phase space data is delivered from Gaia's line-of-sight (radial) velocities for the 300 million brightest stars. These data make substantial contributions to astrophysics and fundamental physics on scales from the Solar System to cosmology. A knowledge revolution is underway.