Institute of Astronomy

Milky Way Galaxy

A major fraction of efforts in modern astrophysics research has been directed towards understanding the formation and evolution of galaxies. It is being increasingly recognised that important clues to this great outstanding problem of astrophysics lie locked up in the motions and chemical composition of stars in our own Galaxy – The Milky Way Galaxy ("near-field/precision cosmology").

The Milky Way is representative of a typical disk Galaxy in the universe and hence becomes the perfect laboratory to explore Galaxy formation. Our vantage point within the Galaxy makes it possible for us to observe common structures of a regular disk galaxy in such detail that we can address questions which cannot otherwise be pursued by the “far-field cormology” (or study of high-redshift galaxies) approach. We are able to pursue a range of investigation including study the properties of individual galactic components such as the Bulge, Bar, Disk and Halo, examine the orbits and angular momentum distribution of stars, quantify the mass distribution in different components etc, which together allow us to understand the chemical and structural evolution of the Galaxy as a whole in the form of the collective effect of isolated or inter-dependent evolutionary histories of its structural components. Local studies also makes it possible for us to verify small scale predictions of galaxy formation theories and study the exact contribution of environment and satellite galaxies to the ongoing process of galaxy evolution.

Large scale surveys (such as Sloan Digital Sky Survey, Radial Velocity Experiment) have propelled the study of stellar populations. Beginning from the discovery of the Thick Disk to ongoing studies to understand its formation mechanism, and the discovery of streams and substructure within the stellar halo which contain hints to the heierarchical formation of the galaxy - the group at the IoA has been in the forefront of stellar population studies. Numerical simulations allow modelling and quantification of this substructure from which one can reconstruct the merger history of the Milky Way. Applying Galactic Dynamics, some members try to understand the the simple underlying dynamical mechanisms and physical processes involved in Galaxy Formation, providing the vital link between simulations and observations.

The big upcoming project in quantifying the structure and formation history of the Milky Way which will revolutionise the field is the ESA satellite – GAIA. GAIA will provide the first census of 1 billion stars in the Milky Way, giving accurate measurements of their positions, motions and chemistry. The IoA leads the reduction and analysis of photometry of GAIA and leads the main ground based follow-up surveys. With the exciting range of discoveries already made possible through survey science, this holds great promise for the future of what we will know about the Milky Way.

Page last updated: 4 October 2011 at 12:03