Say hello to your new neighbour. Astronomers have found a Jupiter-like planet orbiting a star just 12 light years away from Earth, making it the closest confirmed gas giant outside the solar system.
The planet, called Epsilon Indi Ab, has the mass of 2.7 Jupiters and takes an extraordinary 52.6 years to orbit its star – that’s among the longest exoplanet orbits yet discovered. Its star Epsilon Indi is three-quarters the size of our sun, but has just one quarter the luminosity. The system also has two brown dwarfs – objects too big to be gas giants, but too small to be stars – in a binary orbit.
at the University of Hertfordshire in the UK, and his colleagues looked for changes in light from the star that could be caused by an orbiting planet’s gravitational pull. The method, known as radial velocity, is good for finding massive planets, but smaller ones prove trickier because they don’t tug as much on their star.
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When the James Webb Space Telescope launches in 2020, astronomers will study Epsilon Indi Ab even more closely. By looking for changes in the planet’s brightness, they’ll be able to see features like clouds and aurora. “We’ll be able to see if there’s a giant red spot on this planet,” says at the SETI Institute in Mountain View, California.
It’s possible that something even more exciting might be lurking in the Epsilon Indi system too: smaller planets orbiting nearer to the star that are too small to be seen through radial velocity. Some could potentially be Earth-sized, which would mean this neighboring star system is similar to our own.
Solar system analogues seem to be rare among the exoplanets we have found so far. But they’d be useful for astronomers studying what makes a planet habitable. Having one just 12 light years away would be even more valuable. “We could compare it with the solar system to study the habitability of rocky planets in the habitable zone,” says Feng.
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