Scientists have painted the most detailed portrait yet of the planetary system orbiting Barnard’s Star – the Sun’s closest neighbour after Alpha Centauri, just under six light-years from Earth.
“These planets were always going to be hostile, because they’re really close to their star” said Byrne, “Even the outermost planet orbits ten times closer than Mercury orbits the Sun. When you’re that close to your star, and have such little gravity, your atmosphere just gets blown off.”
The researchers say that the planets could have held on to their atmospheres for at most two billion years – much shorter than the system’s 10-billion-year age. Their results are reported in the Monthly Notices of the Royal Astronomical Society.
Being so close to the star has another consequence for the planets: the researchers found that the planets are all tidally locked. In the same way that the Moon only shows one face to the Earth, the Barnard’s Star planets each only show one face to their star. As a result, each planet has one hemisphere locked in eternal daylight; the other, eternal night.
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