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Updated June 01, 2013
There is no wonder that there are many more planets than stars in our galaxy, but some float freely.
A team of astronomers, funded by NASA, discovered a new class of planets floating in the size of Jupiter, traveling alone in the darkness of space, away from the light of a star. The team believes that these isolated worlds were probably ejected during the creation of planetary systems. The discovery is based on a joint investigation Japan-New Zealand who scanned the center of the Galaxy, the Milky Way, between 2006 and 2007. They found 10 exoplanets floating with a mass equivalent to that of Jupiter. These isolated orbs, also known as orphan planets, are difficult to spot, and had not been detected so far. The newly discovered planets are located at an mean distance of approximately 10 000 to 20 000 light years from Earth. "While these floating planets have been predicted, they were finally detected, this finding has major implications for planet formation and evolution models," said Mario Perez, exoplanet program scientist at NASA Headquarters Washington.
The discovery indicates that there is certainly a lot of free floating planets, the mass of Jupiter, which can not be seen. Team estimates that there are at least twice as many planets as stars nomads. These worlds are as common as planets orbiting stars. This would add up to hundreds of billions of planets free in our Milky Way alone. "Our survey is a census of the population," said David Bennett, co-author of the study from the University of Notre Dame in South Bend. "We sampled a portion of the galaxy, and on the basis of these data, we estimated the overall number in the galaxy. "
The study, led by Takahiro Sumi of Osaka University in Japan, was published in the journal Nature, May 19, 2011. The survey does not identify planets smaller than Jupiter or Saturn, but theories suggest that the less massive planets, like Earth, should be even more numerous than the floating Jupiters.
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Image: There are in our galaxy, billions of planets floating, the size of Jupiter and even more, the size of Earth.
Image d'artiste © astronoo.com
Planets or stars?
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Previous observations had already identified a handful of planets floating, as objects in star-forming clusters, with masses, three times that of Jupiter. But scientists suspect that these gaseous bodies look more like failed stars, to planets. These small dark stars called brown dwarfs, with the collapse of the original nebula of gas and dust, did not obtain sufficient mass to ignite their nuclear fuel and shining like stars. On the other hand, it is likely that some planets were ejected from their turbulent solar systems, according to the vagaries and gravitational encounters with other planets or stars. These planets free, travel through the galaxy as our sun and other stars, in stable orbits around the center of the galaxy.
"If floating planets formed like stars, we would see less of the 10 in our investigation," said Bennett.
"Our results suggest that planetary systems often become unstable, and some planets are evicted from their birthplaces."
The observations can not exclude the possibility that some of these planets may have very distant orbits around stars, but other research indicates that the planets of Jupiter's mass, in these distant orbits are rare.
A telescope of 5.9 feet (1.8 meters), located at Mount John University Observatory in New Zealand, is regularly used to scan the stars at the center of our Galaxy, using the method of gravitational microlensing. In astrophysics, an illusion, that astronomers are familiar with, is the gravitational lensing or gravitational mirage. A massive object, a cluster of galaxies, for example, which is between an observer and a distant light source, prints a strong curvature in space-time. This has the effect of deflecting all light rays passing near the object, thereby distorting the images received by the observer. This amplification of the brightness of a distant celestial object, by a massive star in front, was predicted by the theory of general relativity in 1917. Massive objects are changing the geometry of space and time in their neighborhood. Light on it always takes the shortest route, but in a curved space modified by the presence of a huge mass, the shortest path is not straight. The light path is curved in the vicinity of massive stars.
nota: NASA Jet Propulsion Laboratory, Pasadena, Calif., manages the office of NASA's Exoplanet Exploration Program. JPL is a division of the California Institute of Technology in Pasadena.