'Super-Earth' planet shows signs it could have an atmosphere - KSL.com

ATLANTA — Scientists say they have detected promising signs that a planet orbiting a star 49 light-years from Earth could have an atmosphere, making it potentially suitable for life.Called LHS 1140b, the object is about five times the mass of our planet, or a "super-Earth." This planet orbits around its star in the "Goldilocks zone," also known as the habitable zone, meaning its surface temperature is not too hot or too cold for liquid water to exist."We believe it is also predominantly a rocky planet, based on its mass and its radius measurements, which gives us a density estimate," said Collin Cherubim, a planetary scientist and lead author of a paper on the finding, published July 16 in the journal Science."It appears to be consistent with Earth, meaning it might have an iron core and a silicate mantle, plus some sort of low-density component, which is probably a combination of water and, now we know, an atmosphere," said Cherubim, a NASA Sagan Fellow at the University of Chicago. He conducted the research during his doctoral studies at Harvard University.Astronomers have discovered more than 6,200 exoplanets since uncovering the first ones in the 1990s. The Hubble Space Telescope found evidence in 2001 of an atmosphere on a gas giant exoplanet orbiting a star about 150 light-years from Earth.If further observations confirm the findings, LHS 1140b would mark the first discovery of an atmosphere on a rocky planet in the habitable zone of another star.Signs of a habitable planetLooking at the atmospheres of faraway rocky planets is difficult, because these celestial bodies are small and their atmospheres are thin. Astronomers must wait for a planet to move in front of its host star. Similar to an eclipse, as the light filters through the atmosphere, it can reveal the signature of a gas.There is no evidence of life or a life-supporting atmosphere on LHS 1140b now, but Cherubim said he believes it's a formidable candidate for potential signatures of extraterrestrial life."I think it's the best place to look for life outside the solar system at this point," he said. "It's mostly rocky, it's at the right temperature to support liquid water on the surface, and it has an atmosphere — those are the three key ingredients we look for."To spot the atmosphere, Cherubim first developed a model based on the widespread assumption that many planets form with atmospheres dominated by hydrogen and helium — the mo