GAIA -Mapping the Family Tree of the Milky Way
The upcoming European Space Agency's GAIA Mission will map the genealogical family tree of our home galaxy, the Milky Way, conducting a census of one billion stars with resolutions comparable to measuring the diameter of a human hair at a distance of 1000 kilometers.
GAIA's expected scientific harvest is of almost inconceivable extent and implication. Its main goal is to clarify the origin and evolution of our Galaxy by providing tests of the various formation theories of star formation and evolution. This is possible since low-mass stars live much longer than the present age of the universe, and retain a detailed fossil record of their origin in their atmospheres.
The mission will monitor each of its target stars about 70 times
over a five-year period, precisely charting 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 identify tens of
thousands of asteroids.
GAIA will include detection and characterization 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, to galaxies in the nearby universe and about 500,000 distant quasars. It will also provide new tests of Einstein's general relativity theory.
This massive 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.
The GAIA results will precisely identify relics of tidally disrupted accretion debris, probe the distribution of dark matter, establish the luminosity function for pre-main sequence stars, detect and categorize rapid evolutionary stellar phases, place unprecedented constraints on the age, internal structure and evolution of all stellar types, and classify star formation and kinematic and dynamic behavior within the Local Group of galaxies.
GAIA will pinpoint exotic objects in colossal and almost
unimaginable numbers: many thousands of extra-solar planets will be
discovered, and their detailed orbits and masses determined; brown
dwarfs and white dwarfs will be identified in their tens of thousands;
some 20 000 supernovae will be detected and details passed to
ground-based observers for follow-up observations; Solar System studies
will receive a massive impetus through the detection of many tens of
thousands of new minor planets, and even new trans-Neptunian objects,
including Plutinos, may be discovered. Amongst other results relevant
to fundamental physics, GAIA will follow the bending of star light by
the Sun, over the entire celestial sphere, and therefore directly
observe the structure of space-time.
The 16 volumes of the earlier Hipparcos Mission will instead be 160 000 volumes and instead of filling one normal bookshelf, that bookshelf would have to stretch the equivalent distance of Paris to Amsterdam.
Currently there are not very many large samples of halo stars with
sufficiently accurate motions to enable us to break up the velocity
distribution into the hundreds of streams expected. The HIPPARCOS
satellite provided proper motions of about 100 halo stars, which
combined with ground-based observations, allowed astronomers to
discover the first direct indication of a past merger in the Solar neighborhood: a small galaxy probably similar to current satellites of
the Milky Way.
GAIA, was approved in 2000 as an ESA Cornerstone mission to be launched around 2011.
Posted by Casey Kazan
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