“Circumtriple” planet would show planets can form in unusual places.
ESO; L. CALÇADA/EXETER; KRAUS ET AL.
Astronomers have discovered several planets orbiting two stars at once, called circumbinary planets. And now they might have found the first planet orbiting three, The New York Times reports. A star system 1300 light-years from Earth called GW Ori has two stars closely orbiting one another with a third star farther out that circles them, and a huge disk of dust that surrounds all three (artist’s impression, above left). That dusty disk is split into three rings, with a large gap between the inner ring and the other two.
Scientists have debated whether this gap in the ring is a symptom of gravitational torque caused by the three stars, or is instead evidence of the first known “circumtriple” planet carving out its orbit. New modeling points to a massive planet—or even multiple planets—as the best way to explain that gap, scientists report in the Monthly Notices of the Royal Astronomical Society. If confirmed, this could strengthen the idea that planets form more commonly throughout the universe than thought—even in particularly strange systems.