|This artist’s impression shows the newfoun potentially habitable alien planet HD40307g in the foreground, with its host star and two other worlds in the six-planet system also depicted.|
The newfound exoplanet, a so-called "super-Earth" called HD 40307g, is located inside its host star's habitable zone, a just-right range of distances where liquid water may exist on a world's surface. And the planet lies a mere 42 light-years away from Earth, meaning that future telescopes might be able to image it directly, researchers said.
"The longer orbit of the new planet means that its climate and atmosphere may be just right to support life," study co-author Hugh Jones, of the University of Hertfordshire in England, said in a statement. "Just as Goldilocks liked her porridge to be neither too hot nor too cold but just right, this planet or indeed any moons that it has lie in an orbit comparable to Earth, increasing the probability of it being habitable."
HD 40307g is one of three newly discovered worlds around the parent star, which was already known to host three planets. The finds thus boost the star's total planetary population to six.
Finding new signals in the data
The star HD 40307 is slightly smaller and less luminous than our own sun. Astronomers had previously detected three super-Earths — planets a bit more massive than our own — around the star, all of them in orbits too close-in to support liquid water.
In the new study, the research team re-analyzed observations of the HD 40307 system made by an instrument called the High Accuracy Radial velocity Planet Searcher, or HARPS.
HARPS is part of the European Southern Observatory's 11.8-foot (3.6 meters) telescope at the La Silla Observatory in Chile. The instrument allows astronomers to pick up the tiny gravitational wobbles an orbiting planet induces in its parent star.
A candidate for direct observation
Super-Earths have been spotted in other stars' habitable zones before. For example, a team using NASA's prolific Kepler Space Telescope announced the discovery of the potentially habitable world Kepler-22b in December 2011.
Kepler-22b lies 600 light-years away, which is not terribly far considering that our Milky Way galaxy is about 100,000 light-years wide. But HD 40307g is just 42 light-years from us — close enough that future instruments may be able to image it directly, scientists say. Source