Earth may have a twin orbiting one of our nearest stellar neighbors, a new study suggests.
University of California, Santa Cruz graduate student Javiera Guedes used computer simulations of planet formation to show that terrestrial planets are likely to have formed around one of the stars in the Alpha Centauri star system, our closest stellar neighbors.
Guedes' model showed planets forming around the star Alpha Centauri B (its sister star, Proxima Centauri, is actually our nearest neighbor) in what is called the "habitable zone," or the region around a star where liquid water can exist on a planet's surface.
The model also showed that if such planets do in fact exist, we should be able to see them with a dedicated telescope.
"If they exist, we can observe them," Guedes said.
Guedes' study has been accepted for publication in the Astrophysical Journal.
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3 Super-Earths discovered!
A team of European scientists have discovered 45 new exoplanets, including three "super-Earths" orbiting a single Sun-like star.
Scientists detected the extrasolar planets using the HARPS instrument on the 3.4-meter telescope at the European Southern Observatory in Chile. The planets are all less than 30 times the mass of Earth and all orbit very close to their stars. It is easier to detect small planets when they orbit very close to their star, so these are the ones found first.
It was only in 2005 that the first earth-sized exoplanet was discovered and only in April 2007 that the first Earth-sized exoplanet was discovered in the so-called habitable zone (the distance from a star that provides temperatures at which liquid water is stable).
In the most recent discovery, the team found a single Sun-like star that has three super Earths orbiting it, the smallest of which is only 4 times the mass of Earth. The host star, HD 40307, is located 42 light-years away towards the southern Doradus and Pictor constellations. "We have made very precise measurements of the velocity of the star HD 40307 over the last five years, which clearly reveal the presence of three planets," says planet hunter Michel Mayor of the Geneva Observatory.
These planets are orbiting too close to their star to be conducive to life as we know it (they are too hot), but their existence builds the case for smaller planets being common.
This new discovery points to small planets being ubiquitous in the universe. The study looked at over 100 stars that were previously thought not to have planets. More than a third turned out to have planets slightly bigger than Earth.
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