Continued support for the RAVE survey

The dominant stellar component of our Galaxy is its disc - the Sun is a part of this disc, so in every direction the disc surrounds us. The RAVE survey is a major international effort to determine the structure and history of the disc by measuring the velocities and chemical compositions of a million stars spread over the southern hemisphere. From the velocities measured it will be possible to determine the mass density throughout a sphere centred on the Sun that is several thousand light years in radius. The difference between this mass density and the observed density of stars and gas we will determine the local distribution of the mysterious dark matter that makes up more than 80% of the mass of the Universe. Within the data taken we expect to be able to identify the relics of star clusters and dwarf galaxies that have been pulled apart by the Galaxy's gravitational field. A census of such objects will help us to understand the Galaxy's star-formation and accretion history. Additional insight into the Galaxy's star-formation history will be obtained from chemical composition measurements. The data will also reveal changes in the velocities of the stars caused by the Galaxy's spiral arms, and thus deepen our understanding of the important phenomenon of spiral structure.