Issue |
Astron. Astrophys. Suppl. Ser.
Volume 116, Number 3, May 1 1996
|
|
---|---|---|
Page(s) | 579 - 595 | |
DOI | https://doi.org/10.1051/aas:1996136 | |
Published online | 15 May 1996 |
GAIA: Global astrometric interferometer for astrophysics
1
Lund Observatory, Box 43, S-22100 Lund, Sweden
2
Astrophysics Division, European Space Agency, ESTEC, Noordwijk 2200AG, The Netherlands
3
Sterrewacht Leiden, Postbus 9513, 2300RA Leiden, The Netherlands
Send offprint request to: L. Lindegren
Received:
11
July
1995
Accepted:
4
October
1995
GAIA is a preliminary concept for an astrometric mission,
recently recommended within the context of ESA's `Horizon 2000 Plus' long-term
scientific programme. In its present form, the experiment is
estimated to lead to positions, proper motions, and
parallaxes of some 50 million objects, down to about mag, with
an accuracy better than 10 microarcsec, along with multi-colour
multi-epoch photometry of each object. The scientific case for such a
mission is dramatic: distances and
kinematical motions for tens of millions of objects, throughout
our Galaxy, would be obtained—the expected accuracy is such that
direct (trigonometric) distance estimates to the galactic centre would
be accurate to 10%, with transverse motions accurate to about
1 km s-1 at 20 kpc. As `by-products', the global
measurements would yield unprecedented information on the space-time metric
(γ to a precision of about 1 part in 106 or better, close to values
which might distinguish currently competing theories of gravity), angular
diameters of hundreds of stars, and a vast body of information on
double and multiple systems. Perhaps the most dramatic of these
subsidiary goals would be the possibility of screening some
stars within 100 pc for periodic photocentric motions, which would
provide the most powerful and systematic method of detecting possible
planetary companions proposed to date.
Key words: astrometry / space vehicles / planetary systems / relativity / instrumentation: interferometers / Galaxy: general
© European Southern Observatory (ESO), 1996