Research
Since many years ARI is active in
astrometry
and was especially involved in the data reduction of
HIPPARCOS.
That mission measured
120,000 stars, while the forthcoming satellite project
Gaia - a cornerstone mission of the
European Space Agency ESA to be launched in 2011 - will collect even better
data for more than 1 billion stars.
The Gaia data reduction and scientific analysis is split into different
sub-projects, where ARI is most engaged in the Core Processing, the
First Look, and the
establishment of the Gaia data archive. The scientific analysis of the Gaia data
will result in a major improvement in our
understanding of the formation and
evolution of the Milky Way.
In
stellar dynamics the structure, dynamics and mass distribution of
stellar systems are investigated. This ranges from
planet formation, evolution of star clusters, the Milky Way and other galaxies,
to cosmological topics.
Beside the realisation and data interpretation of observations, numerical
simulations of the evolution of stellar systems are in the foreground.
The ARI has comprehensive experience with parallel computing; computer networks
are used in the numerical simulations, which are additionally provided with
special hardware for the computation of many gravitational interactions
(GRAPE-Boards).
A new 64-processor parallel computer was just built up, as part
of the projects
GRACE
(Volkswagenstiftung) and
SFB439 .
The research on
galaxy evolution
concentrates partly on our Milky Way and nearby galaxies,
where single stars can be resolved, and partly on the integrated
light of distant galaxies and galaxy clusters. The investigation of the
structure, dynamics and evolution of spiral and dwarf galaxies is based mainly
on the analysis of the stellar populations (including the physics of White
Dwarfs and star clusters), which
allows a detailed 'galactic archeology'. Large international projects like
RAVE,
SDSS,
and
Pan-STARRS,
where the ARI participates, provide a significant part of the observational
data. The observational part is complemented by complex chemodynamical and
cosmological simulations. In the case of distant galaxy clusters also X-ray
observations are used.
Gravitational lensing
is the deflection of light by massive objects in
the universe. This changes the positions of background objects,
magnifies them and distorts their shape. The most spectacular phenomena
are multiple images (two or more) of a single background source. At the
ARI multiply imaged quasar are studied with respect to brightness
changes, light curves, time-delay determination and microlensing.
Moreover, gravitational lensing is used to discover planets around other
stars.
The ARI compiles, produces and updates a number of
astronomical catalogues, like the
ARIAPFS (database of the Apparent Places of the Fundamental Stars)
ARICNS (database of the Nearby Stars)
ARIHIP (astrometrically improved data of the satellite HIPPARCOS)
FK6 (6th catalogue of the fundamental stars).
Additionally to the main goal - the preparation of astrometric data -
in ARICNS a variety of astrophysical data are included and ARIHIP contains
detailed information on the binary nature of the catalogue stars.
Contact: A. Just
