杏吧原创

About 370 light years away, a planet is being born 鈥� and with that exoplanet, possibly a set of rings or moons. In 2018, astronomers spotted a young world growing around a star called PDS 70. Now they have observed what appears to be a disc of debris orbiting the planet, the same sort of disc that we think can coalesce into a moon.

The researchers used the Very Large Telescope in Chile to examine the spectrum of the light coming from the planet, PDS 70b, and found that it appeared to be emitting more infrared light than we would expect for just a planet on its own.

That infrared light indicates that something above the planet鈥檚 surface is being heated as it absorbs light from the planet and re-emits it at a longer and redder wavelength. They compared the data with models of a planetary atmosphere and a disc of dust and gas, and found that the disc was a far better match.

鈥淚f you were on the planet you would burn, because it鈥檚 covered in lava,鈥� says team member Faustine Cantalloube at the Max Planck Institute for Astronomy in Heidelberg. 鈥淭he planet is very, very young, it鈥檚 still forming, so it鈥檚 hot and bright and it鈥檚 heating up this dust around the planet.鈥�

This is the first time we have spotted one of these discs around a young planet. Some of its material is probably falling onto the planet and helping it grow, but eventually the disc may flatten out to form rings like Saturn鈥檚 or even clump up and create moons. We have never definitively spotted a moon around a planet outside our solar system.

鈥淔rom the surface it might look like a huge dust cloud or a storm rotating around the planet,鈥� says Cantalloube. 鈥淭he planet is still feeding the ring and vice versa, so there might be material flowing back and forth.鈥� Understanding this process better might help us hone our knowledge of how planetary systems form.