“Most planets we have found to date are scorched. This system is the closest star with lukewarm transiting planets,” says Erik Petigura. Above, artist’s impression of the Kepler spacecraft. (Credit: NASA Ames/JPL-Caltech/T Pyle)
3 EARTH-SIZE PLANETS ORBIT ‘EPIC’ NEW STAR
UNIVERSITY OF ARIZONA, UNIVERSITY OF CALIFORNIA, BERKELEYrightOriginal Study
Posted by Doug Carroll-Arizona on January 20, 2015
Scientists have discovered a new star with three nearly Earth-sized planets—one of which may have temperatures moderate enough for liquid water—and maybe even life—to exist.
NASA’s Kepler Space Telescope was able to find the star, EPIC 201367065—a cool red M-dwarf about half the size and mass of our own sun, despite being hobbled by the loss of critical guidance systems, .
At a distance of 150 light-years, it ranks among the top 10 nearest stars known to have transiting planets. The star’s proximity means it is bright enough for astronomers to study the planets’ atmospheres, to determine whether they are like Earth’s—and possibly conducive to life.
“A thin atmosphere made of nitrogen and oxygen has allowed life to thrive on Earth. But nature is full of surprises,” says Ian Crossfield, an astronomer at University of Arizona who led the study. “Many exoplanets discovered by the Kepler mission are enveloped by thick, hydrogen-rich atmospheres that are probably incompatible with life as we know it.”
ROCKY LIKE EARTH
The three planets are 2.1, 1.7, and 1.5 times the size of Earth. The smallest and outermost planet, at 1.5 Earth radii, orbits far enough from its host star that it receives levels of light from its star similar to those received by Earth from the sun, says Erik Petigura, a graduate student at University of California, Berkeley.
Petigura discovered the planets January 6 while conducting a computer analysis of the Kepler data NASA has made available to astronomers. In order from farthest to closest to their star, the three planets receive 10.5, 3.2, and 1.4 times the light intensity of Earth.
“Most planets we have found to date are scorched. This system is the closest star with lukewarm transiting planets,” Petigura says. “There is a very real possibility that the outermost planet is rocky like Earth, which means this planet could have the right temperature to support liquid water oceans.”
Extrasolar planets are discovered by the hundreds these days, although many astronomers are left wondering if any of the newfound worlds are really like Earth, says Andrew Howard, an astronomer at University of Hawaii. The newly discovered planetary system will help resolve this question.
“We’ve learned in the past year that planets the size and temperature of Earth are common in our Milky Way galaxy,” he says. “We also discovered some Earth-size planets that appear to be made of the same materials as our Earth, mostly rock and iron.”