June 27, 2013
In the habitable zone around the star Gliese 667C scientists have found three planets that could be suitable for life. The star is 22 light-years from Earth and it has at least six planets around it, possibly seven. This is the first time that we found three extrasolar planets orbiting a single star in the zone where liquid water is possible.
Three planets in the habitable zone around Gliese 667C.
Gliese 667C is part of a three-star system. It was previously thought that it had three planets orbiting it, but when researchers at European Southern Observatory took another look, they found out that it has three, possibly four more planets. Three of these planets are in the zone where the surface temperatures are just right for the water to be liquid, thus being able to support life. Planets would also have to be made of rock, which is probably the case, considering their size.
"We knew that the star had three planets from previous studies, so we wanted to see whether there were any more," member of the study Mikko Tuomi of the University of Hertfordshire, UK said. "By adding some new observations and revisiting existing data we were able to confirm these three and confidently reveal several more. Finding three low-mass planets in the star's habitable zone is very exciting!"
Gliese 667C has only 31% of the Sun's mass and 42% of the Sun's radius. It is the smallest of the three stars in the system, other two being Gliese 667A and Gliese 667B. This sheds a new light on what we can expect to find around low-mass stars. "The number of potentially habitable planets in our galaxy is much greater if we can expect to find several of them around each low-mass star - instead of looking at 10 stars to look for a single potentially habitable planet, we now know we can look at just one star and find several of them," Rory Barnes of the University of Washington says.
ESO scientists think that the habitable zone around Gliese 667C cannot support more than three planets. Considering the size of the star, as well as it's low brightness, compared to our Sun, the habitable zone is relatively near the star, comparable to the Mercury's distance to the Sun.