GAIA: Composition, formation and evolution of the Galaxy

¹ Astrophysics Division, Space Science Department of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
² Sternwarte Univ. Bonn, Auf dem Hugel 71, 53121 Bonn, Germany
³ University of Cambridge, Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK
⁴ Copenhagen University Observatory, Juliane Maries Vej 30, 2100 OE Copenhagen, Denmark
⁵ Osservatorio Astronomico di Torino, Strada Osservatorio 20, 10025 Pino Torinese (TO), Italy
⁶ Lund Observatory, Box 43, 22100 Lund, Sweden
⁷ Universitat de Barcelona, Departament d'Astronomia i Meteorologia, Avda Diagonal 647, 08028 Barcelona, Spain
⁸ Observatoire de la Côte d'Azur, CERGA, Avenue Copernic, 06130 Grasse, France
⁹ Future Projects Division of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
¹⁰ Sterrewacht, Jan Hendrik Oort Building, Postbus 9513, 2300 RA Leiden, The Netherlands

Corresponding author: M. A. C. Perryman, mperryma@astro.estec.esa.nl

Received: 1 November 2000
Accepted: 5 January 2001

Abstract

The GAIA astrometric mission has recently been approved as one of the next two "cornerstones"of ESA's science programme, with a launch date target of not later than mid-2012. GAIA will provide positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and kinematic census of about one billion stars throughout our Galaxy (and into the Local Group), amounting to about 1 percent of the Galactic stellar population. GAIA's main scientific goal is to clarify the origin and history of our Galaxy, from a quantitative census of the stellar populations. It will advance questions such as when the stars in our Galaxy formed, when and how it was assembled, and its distribution of dark matter. The survey aims for completeness to mag, with accuracies of about 10 μas at 15 mag. Combined with astrophysical information for each star, provided by on-board multi-colour photometry and (limited) spectroscopy, these data will have the precision necessary to quantify the early formation, and subsequent dynamical, chemical and star formation evolution of our Galaxy. Additional products include detection and orbital classification of tens of thousands of extra-Solar planetary systems, and a comprehensive survey of some minor bodies in our Solar System, through galaxies in the nearby Universe, to some 500 000 distant quasars. It will provide a number of stringent new tests of general relativity and cosmology. The complete satellite system was evaluated as part of a detailed technology study, including a detailed payload design, corresponding accuracy assesments, and results from a prototype data reduction development.