Mapping One Billion Stars In The Milky Way And Beyond

Science@ESA Vodcast (Episode 6, Part 2): Charting the Galaxy ... from Hipparcos to Gaia - Mapping one billion stars in the Milky Way and beyond.

In this sixth episode of the Science@ESA vodcast series Rebecca Barnes discovers the motions of the stars, learns how astronomers measure their distances and looks at the new European mission that will really get to grips with our place in the Universe.

Gaia is a global space astrometry mission. Its goal is to create the largest and most precise 3-D chart of our Milky Way galaxy by providing unprecedented positional and radial velocity measurements for about one billion stars in our galaxy and throughout the Local Group.

ESA GAIA MISSION

Gaia is an ambitious mission to chart a three-dimensional map of our galaxy, the Milky Way, in the process revealing the composition, formation and evolution of the Galaxy. Gaia will provide unprecedented positional and radial velocity measurements with the accuracies needed to produce a stereoscopic and kinematic census of about one billion stars in our Galaxy and throughout the Local Group. This amounts to about one percent of the Galactic stellar population.

Combined with astrophysical information for each star, provided by on-board multi-colour photometry, these data will have the precision necessary to quantify the early formation, and subsequent dynamical, chemical and star formation evolution of the Milky Way Galaxy.

Additional scientific products include detection and orbital classification of tens of thousands of extra-solar planetary systems, a comprehensive survey of objects ranging from huge numbers of minor bodies in our Solar System, through galaxies in the nearby Universe, to some 500.000 distant quasars. It will also provide a number of stringent new tests of general relativity and cosmology.

• http://sci.esa.int/science-e/www/area...

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Gaia will conduct a census of a thousand million stars in our Galaxy, monitoring each of its target stars about 70 times over a five-year period. It will precisely chart their positions, distances, movements, and changes in brightness. It is expected to discover hundreds of thousands of new celestial objects, such as extra-solar planets and failed stars called brown dwarfs. Within our own Solar System, Gaia should also observe hundreds of thousands of asteroids.

Additional scientific benefits include the detection and characterisation of tens of thousands of extra-solar planetary systems, a comprehensive survey of objects ranging from huge numbers of minor bodies in our Solar System, through galaxies in the nearby Universe, to about 500 000 distant quasars. It will also provide stringent new tests of Albert Einsteins general relativity theory.

Gaia will rely on the proven principles of ESAs Hipparcos mission to create an extraordinarily precise three-dimensional map of more than a thousand million stars throughout our Galaxy and beyond. Gaia will also map the motions of stars, which encode their origins and evolution. Gaia will provide the detailed physical properties of each star observed, revealing luminosity, temperature, gravity and composition. This huge stellar census will provide the basic observational data to tackle an enormous range of important problems related to the origin, structure and evolutionary history of our Galaxy.

At its heart, Gaia contains two optical telescopes that can precisely determine the location of stars and split their light into a spectrum for analysis. The spacecraft itself can be divided into two sections: the payload module and the service module. The payload consists of the telescopes and three instruments. The service module contains the propulsion system, the communications units and other essential components that allow the spacecraft to function and return data to Earth. Beneath the service module and the payload module is the sunshield and solar array assembly.

• http://www.esa.int/export/esaSC/12037...