Astronomers Spot Two New Jupiter-Sized Planets Orbiting Twin Stars

Astronomers have spotted two new Jupiter-sized planets orbiting a stars in a binary-star system. The findings reveal an unusual case for the extra-solar planets, most of which orbit stars that are alone.

Many stars are part of binary systems, which are twin stars that form out of the same gas cloud. Yet these two-star systems often don't have planets. Now, for the first time, two stars of a binary system are both found to host a "hot Jupiter" exoplanet.

The researchers first spotted the stars and planets when they found tiny tips in the light of WASP-94A, one of the stars. This suggested that a Jupiter-like planet was transiting the star. Then, they spotted WASP-94B and found that it, too, had a planet.

Hot Jupiter planets are far closer to their stars than our own Jupiter. They are relatively rare, so this latest finding is extraordinary. Currently, scientists believe that hot Jupiters form much further out, where it is cool enough for ices to freeze out of the proto-planetary disk circling a young star. Then the planet eventually moves into a closer orbit.

The findings could potentially help researchers understand a bit more about these hot Jupiters. More specifically, it could tell scientists exactly what causes the hot Jupiters to move inward toward their host stars after they first form.

"WASP-94 could turn into one of the most important discoveries from WASP-South," said Coel Hellier, one of the researchers, in a news release. "The two stars are relatively bright, making it easy to study their planets, so WASP-94 could be used to discover the compositions of the atmospheres of exoplanets."

The findings are published in the journal Astronomy and Astrophysics.