From Hipparcos to Gaia

TL;DR

The paper reviews the progression from the Hipparcos satellite to the Gaia mission, highlighting advancements in astrometric precision, star catalog size, and the broad scientific impact on astrophysics over recent decades.

Contribution

It provides an overview of the evolution from Hipparcos to Gaia, emphasizing technological improvements and expected scientific breakthroughs in stellar and galactic studies.

Findings

Hipparcos improved position accuracy by 100 times over ground-based results.

Gaia will increase star catalog size by a factor of 10, reaching one billion objects.

Gaia's data will significantly advance understanding of the Milky Way and exoplanet detection.

Abstract

The measurement of the positions, distances, motions and luminosities of stars represents the foundations of modern astronomical knowledge. Launched at the end of the eighties, the ESA Hipparcos satellite was the first space mission dedicated to such measurements. Hipparcos improved position accuracies by a factor of 100 compared to typical ground-based results and provided astrometric and photometric multi-epoch observations of 118,000 stars over the entire sky. The impact of Hipparcos on astrophysics has been extremely valuable and diverse. Building on this important European success, the ESA Gaia cornerstone mission promises an even more impressive advance. Compared to Hipparcos, it will bring a gain of a factor 50 to 100 in position accuracy and of a factor of 10,000 in star number, collecting photometric, spectrophotometric and spectroscopic data for one billion celestial objects. During its 5-year flight, Gaia will measure objects repeatedly, up to a few hundred times, providing an unprecedented database to study the variability of all types of celestial objects. Gaia will bring outstanding contributions, directly or indirectly, to most fields of research in astrophysics, such as the study of our Galaxy and of its stellar constituents, the search for planets outside the solar system.