Image of the Day: A Billion Stars of the Milky Way



British scientists have produced a colossal picture of our Milky Way Galaxy that reveals the detail of a billion stars. The iamge was built from thousands of individual images acquired by two UK-developed telescopes operating in Hawaii and in Chile, and concentrates on the dense plane of the galaxy, which means it renders as a very long, very thin strip. An online interactive tool allows you to zoom in to particular areas.

Archived data from the project, known as the Vista Data Flow System, will be mined by astronomers to make new discoveries about the local cosmos.

To get an even better view, University of Cambridge astronomers are now initiating a European-wide program, hailed as the premier European astrophysics space mission of the decade, to create the first 3D map of these billion stars in more detail.

With the largest digital camera ever built, the Gaia satellite, due to be launched into space in August 2013, will feed billion-pixel video data in three dimensions of a billion stars, galaxies, quasars, and solar system asteroids to a powerful data center at the Institute for Astronomy (IoA).

In 1989, the European Space Agency (ESA) launched Hipparcos, the first — and so far the only — satellite to chart the positions of stars, which produced a primary catalogue of about 118,000 stars, followed by a secondary catalogue, called Tycho, of over 2 million stars. Since Hipparcos was launched, Gaia will be able to measure a star’s position and motion 200 times more accurately, and will measure one billion stars.

In order to process the five years of Gaia’s photometric data, the team has worked for several years to develop a system that can calibrate the raw transmitted photometric data. Even highly compressed, the data transmitted by the satellite over the five-year mission would fill over 30,000 CDROMs (1300 DVDs or ~20 TB). Many times that amount will be produced during the processing of the data as intermediate results of computations.

The new installation has 108 processing servers, each have with two 6-core CPUs, 48 gigabytes of RAM, and 9 terabytes of hard-disk storage, a total of nearly 1 petabyte (1000 terabytes) of hard-disk storage. The system will process the photometric data from Gaia during the 5-6 years of mission operation, and for two years afterwards, to produce a calibrated set of measurements which can be freely used by the astronomical community.

Its two optical telescopes are capable of measuring the positions of celestial objects to an accuracy of up to 10 microarcseconds, comparable to the diameter of a human hair at a distance of 1000 km. To determine the properties of stars, Gaia will also split their emitted light into a spectrum before communicating the data back to Earth.

Gaia is expected to discover a multitude of new objects both in our solar system, including brown dwarfs and white dwarfs, supernovae and extra-solar planets; probe the distribution of dark matter; discover new asteroids; map over 500,000 quasars in the Universe; and measure the local structure of space-time.



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