A frozen Earth-like planet circling just one of a pair of stars has greatly improved the prospects of finding extra-terrestrial life, astronomers claim. The new planet, located 3,000 light years away, is twice as big as Earth and almost exactly the same distance from its parent star as the Earth is from the Sun. But sadly, because the host star shines 400 times less brightly than the Sun, it’s a frozen and almost certainly lifeless world. Until the discovery, no-one realised rocky planets could form stable orbits round one member of a binary star system.
This greatly expands the potential locations to discover habitable planets in the future. Half the stars in the galaxy are in binary systems. We had no idea if Earth-like planets in Earth-like orbits could even form in these systems.
US astronomer Professor Scott Gaudi, from Ohio State University
Planets orbiting pairs of binary stars are relatively common. But the astronomers point out that the same planet orbiting a Sun-like star would be in the “habitable zone” where conditions are potentially suitable for liquid surface water and life. The planet was found by chance when scientists spotted an unusual signal in light from a “microlensing event”. This occurs when a star’s gravity acts like a lens, bending light from a much more distant object precisely behind it.
Without microlensing, it would be extremely difficult or near impossible to detect such a planet, a relatively small planet orbiting relatively far away from a very dim star.
study lead author Andrew Gould, astronomer at Ohio State University