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Thursday, July 5, 2012

STARDUST



The mystery of how dying stars eject the material to form new planets has occupied scientists for decades. A team of astronomers from Europe and Australia managed to decipher the enigma now. We know that stars like the Sun launched into space much of its mass toward the end of his life, but it was unclear how these particles fail off. The researchers used the powerful tools of VLT European Space Agency (Very Large Telescope and Very Large Telescope), located in the Atacama Desert,


to detect dust particles and silicon stars of only a millionth of a meter in length. "It's as if an observer was found in Sydney and could see a cup of coffee at a table in Melbourne and measure its size," he told the BBC Barnaby Norris, University of Sydney, one of the authors. It was thought that the dust grains formed around stars and absorbed its light until they were expelled at high speed into space. However, computer models that recreate that kind of events suggested that the dust particles would be heated by absorbing too starlight, evaporating before being expelled. By measuring the silicon grains, the astronomers found that their size is much larger than previously thought and instead of absorbing the reflected light of the sun like tiny mirrors, remaining at lower temperatures without being destroyed and then being driven by light.

* Storm * Dust particles and material moving in space until they become new planets or nebulae are incorporated into cradles of stars. "The sand grains are converted into blocks of planets. Our own Earth formed from star dust. We have taken a big step in understanding the cycle of life and death," said Albert Zijlstra, University of Manchester, in England, another of the researchers. In an effect similar to a sand storm, particles or dust grains and silicon reach speeds of 30,000 kilometers per hour. The storms produced by the end of the life of a star produce winds 100 million times the solar wind. Scientists estimate that the Sun will begin the process of expulsion of gas in about five billion years. The researchers solved the mystery of stardust while studying the deaths of three red giants, stars that in the past were like the Sun but have exhausted its core hydrogen into helium by nuclear fusion. When you start burning hydrogen around the stellar core, the outer layers increase in size and become colder. For Norris, "the mechanism that escapes the mass of these stars is one of the big questions of astronomy. In this great puzzle, our study provides a small piece." The study was published in the journal Nature.

MEASURES
   
* They have the most precise measurements between galaxies since the universe is accelerating. * International collaboration Sloan Digital Sky Survey (SDSS-III) presented the most precise measurements obtained at the time of the distances to 300,000 galaxies reaching the distant universe. These results provide an unprecedented look at the time the expansion of the universe began to accelerate, whose discovery was made the Nobel Prize in Physics last year. After more than two years of project work Baryon Oscillation Spectroscopic Survey (BOSS), a collaborative project of the SDSS-III, the results are now presented. On March 30 there were obtained the most precise measurements to date of the distances to 300,000 galaxies reaching the distant universe, according to records six articles published in the digital repository arXiv. One of the most surprising discoveries of the last two decades in astronomy, awarded the Nobel Prize for Physics in 2011, was the realization that our universe is not only expanding but that expansion is accelerating, possibly as a result of action called dark energy, whose nature is unknown. 

The purpose of the BOSS project to try to address this problem was to perform a wide mapping of the greater number of galaxies with accurate measurements of their distances. From these measurements, astronomers can deduce the history of the universe's expansion and its rate of acceleration. BOSS started taking data in mid-September 2009 with a new spectrograph attached to the 2.5-meter telescope of the SDSS in the Apache Point Observatory in New Mexico, USA In just two and a half, this experiment has measured the exact positions of 300,000 galaxies across the sky, which can be traced back to the past of our universe, to more than 6,000 million years. BOSS will continue to collect data until 2014, when it will complete the ultimate mapping, which will triple the size of which has been analyzed so far. The sky survey conducted by BOSS reproduces a map of galaxies and clusters of galaxies grouped in walls and filaments, with huge gaps that separate these structures. All these structures arose from small variations in density in the early Universe that bore the stamp of the baryon acoustic oscillations (BAO), a sound wave that spread through the early universe through matter, which later begin to collapse to form galaxies. Billions of years later, the footprint of the BAO can still be recognized in the Universe. This pattern can be interpreted as a cosmic fingerprint reflected in the distribution of galaxies. The details of this fingerprint can be measured parameters of the Universe and the properties of dark energy. In other words, in the same way that fingerprints are unique to each person, the cosmic fingerprint to determine how the universe. With the data taken to date, BOSS has been able to measure the BAO with an error of 2%, more accurate measurement of this data on to date. The map produced by BOSS can see the universe when I was half its current age and see when it begins to accelerate its expansion.


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