Astronomy and Astrophysics Institute
The IAA is involved in theoretical and observational research activities in various fields of astrophysics. These concern in particular the synthesis of atomic nuclei, the chemical and isotopic composition of the solar system and of stars from our Galaxy, the structure and evolution of low- and intermediate-mass stars including diferent mixing processes as well as the modelling of binary systems and of stellar hydrodynamic phenomena of the detonation type. The modeling of the above phenomena is compared with observed quantities, like the chemical composition of stars from various classes. The chemical composition is derived using the best tools, both observational (telescopes and spectrographs from the European Southern Observatory, or from our own high-resolution spectrograph HERMES) and theoretical (model atmospheres, atomic and molecular data). Similarly, nucleosynthesis predictions require many nuclear data which are collected and evaluated, or generated in large-scale theoretical calculations. They are used to generate extended nuclear reaction networks which are made available to the astrophysical community. Besides these research topics where I.A.A. has long been recognized has an international centre of excellence, I.A.A. nowadays contributes substantially to the preparation of the E.S.A. Gaia mission. Astrometry and galactic dynamics are therefore two new active research fields at I.A.A.
Preparation of the ESA Gaia mission
Gaia is the space astrometry mission of the European Space Agency to be launched in 2011. Over a period of five years, it aims at observing 1.2 billion stars for which accurate position and motion (as well as some astrophysical parameters) will measured. IAA hosts several components of the coordination unit (CU) 4 of the Gaia Data Processing and Analysis Consortium. That CU is built upon several Development Units (DU) spread all over Europe. Those DU are in charge of writing, testing, ... the codes that will become the Gaia data reduction pipeline later on. There are thus key entities in the success of the mission. Two of these DU are based at IAA. One is composed of two postdocs and one computer scientist who are responsible for the codes for eclipsing binaries (one star orbiting an other and sometime blocking the light from the latter). That DU is essentially founded through an ESA Prodex grant. The second DU is in charge of the astrometric and resolved binaries. The former correspond to objects whose duplicity is noted through a careful inspection of their motion whereas the latter clearly appear as double on the detector. That second DU is founded by FNRS and the European Commission (Research and Training Network). The manager of the entire CU4 belongs to IAA.