23 Nov 1998

ESA's plans for a microarcsec space astrometry mission being presented at the GAIA workshop

Hosted by The Lorentz Center and Leiden Observatory (University of Leiden), the workshop will provide scientists with the opportunity to learn about the current status and scientific prospects of GAIA. They will also have the opportunity to participate in discussions aimed at consolidating the scientific and technical report to be prepared for the ESA advisory groups.

GAIA (Global Astrometric Interferometer for Astrophysics) is an advanced astrometric mission proposed, in 1995, as a Cornerstone Mission within the ESA Horizon 2000+ science plan, which aims:

• to measure distances and velocities of more than a billion stars in our Galaxy

• to provide:
  
  • highly accurate astrometric data: positions, distances and proper motions (10 microarcsecond at 15 mag);
  • multiplicity and orbital motions;
  • multi-colour photometry at hundreds of separate epochs;
  • radial velocities (a few km/sec at 17 mag).

• its unprecedented accuracy (2-3 orders of magnitudes more accurate than Hipparcos, and five orders of magnitude more accurate than ground observations);

• its extremely large sample observational capabilities (with one billion stars, the catalogue will be 10,000 times larger than Hipparcos; and it will observe 1 per cent of the total number of stars in our Galaxy);

• its very faint limiting magnitude (at 20 mag, more than 5 orders of magnitude fainter than the completeness limit of Hipparcos);

• its on-board source detection and measurement capabilities complete to the detection limit of about 20 mag. This will ensure complete and unbiased samples at the faintest magnitudes, and will mean that variables, burst sources, lensing events, etc will be measured as they occur.

As a result GAIA will uniquely address astrophysical issues such as:

• the formation and evolution of our Galaxy;

• dynamics of the Local Group Galaxies;

• the occurrence and statistics of planetary systems (some 200,000 stars within 200 parsec will be rigorously scrutinised for the presence of Jupiter mass planetary companions);

• wide angle space metric analyses;

• the luminosity and dynamics of rare astrophysical objects.

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Hipparcos homepage

Lorentz Center, Leiden

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