It appears from our home Galaxy is very good appetite! Still milky Way regularly "eats" small galaxies and star clusters, and the deeper they fall into its area of gravitation, the stronger draws them in. However, in this gluttony positive side - swallowed all the stars become part of our Galaxy.

Slonovski digital sky survey (Sloan Digital Sky Survey, or SDSS) is a high - tech project, a large-scale study of images and spectra of stars and galaxies in motion the 2.5-meter wide-angle telescope in the Observatory Apache point, new Mexico. The project is named after businessman and BLAGOTVORITEL Alfred P. Sloan.

It started in 2000, when started mapping quarter ski the celestial sphere. The global task was: to receive more than 100 million images of objects and their spectra. In the avalanche of the obtained data, the average value of red shift of galaxies ranged from z=0.1 to z=0,4, for quasars this value was equal to five, and Champions among quasars had z=6!

By the beginning of the second phase of the project (SDSS-II) was 2006. It was then increased observation of the structure and stellar structure of our Galaxy, the milky Way, and were launched observations of supernovae (pracy SEGUE and Sloan Supernova Survey). This is very important because Ia supernovae are "verst posts" galactic distances: it is defined by the range to far galaxies. Well, in the middle of 2008 is a phase of SDSS-III, it is planned for completion in 2014.

You should tell a little about the unique equipment of the SDSS project. Its 2.5-meter wide angle optical telescope captures using photometric system of five filters (their names U, G, R, I, and Z). Observable objects are classified as point, i.e. stars (determine their magnitude) and long - galaxies.

Telescope camera consists of 30 CCD chips with a resolution of 2048 x 2048 pixels each, i.e. a total complexity of about 120 megapixels. Chips are arranged in five rows of six pieces in each row. Each line has different optical filters with wavelengths from 354, 476, 628, 769 and 925 nm to values 24,4, 25,3, 25,1, 24,4 and 22.9 with a signal-to-noise ratio equal to 5. The location of the following filters: R, I, U, Z, G. Reduced noise of the camera is achieved by cooling to 190 degrees Kelvin (about -80 degrees Celsius) with the help of liquid nitrogen.

Spectroscopy of selected objects is planned: the telescope can record up to 640 spectral records simultaneously through fiber optic cables, dropped into holes drilled in the aluminum plate. The overnight session, use six to nine plates for spectral record, eventually recorded 200 gigabytes of data.

It should be noted that the field survey telescope is more than 7,5 thousand square degrees in the Northern galactic hemisphere. During his work has been obtained data about approximately 2 million objects, spectra of more than 800 thousand galaxies and information about 100 thousands of quasars. Information about the positions of objects and distances between them vividly displays the structure of the Universe.

In the framework of the project Sloan Extension for Galactic Understanding and Exploration, SEGUE to the milky Way was created detailed three-dimensional map, which includes spectra of 240 thousand stars (with radial velocity of about 10 km/s). Data SEGUE present age, composition and distribution in the phase space of stars within the various galactic components. This is the understanding of the structure, formation and evolution of our Galaxy. Opening in 23 kiloparsecs from the Sun object Segue 1, of the galaxy-the satellite of the milky Way, it was surprising - after all, this galaxy has a record density of dark matter in its composition.

Data SDSS available - true-color image of any region of the sky can be obtained after setting the required coordinates. Usage is possible (within the program of NASA World Wind) both Amateurs and professionals. The eighth release of the data DR8 released for users in 2011: using different search interfaces presents images, directory, images, spectra and redshift objects. It was also clarified the distribution of galaxies and properties of stars in our Galaxy, "captured" quasars within the observable Universe, in 2012, made up the largest three-dimensional map of massive galaxies and black holes.

Of the latest discoveries in the framework of the project SDSS-III - detection of injected into the milky Way flow of the stars, the remnant of an ancient star cluster, which is absorbed in our Galaxy. This thread is very narrow and not explicitly galactic. He was named "thread Triangle", this is the first thread, found in the southern region of the Galactic sky. Such streams of stars is now visible in the Northern and southern Galactic hemisphere is a small galaxies and star clusters in the phase "devouring" them Milky Way, our giant Galaxy.

The study authors write: milky Way constantly "eats" small galaxies and star clusters, the deeper they fall into its area of gravitation, the stronger draws them in, and the stars become part of our Galaxy". And associate Professor of astronomy at Yale University Marla JICA says: "Our discovery is rather "light snack"than "hearty dish" for the milky Way, a detailed study of this process is important because it gives us a new understanding of how to shape and develop all galaxies".

Thus confirmed the assumption that extended objects form a hierarchical structure through mergers and acquisitions, when large unit increase at the expense of smaller galaxies and local star clusters. This process is the main method of increasing the weight of large galaxies similar to the Milky Way.