The recent discovery of a pair of binary planets has astronomers scratching their heads in wonder. This pair of planets has been so far difficult to classify, as they display characteristics of both brown dwarfs (failed pseudo-stars) and gas giants. So-called binary planets, or pairs of planets that orbit one another around a central point, are a rare phenomenon. It’s much more common for planets to orbit stars, which have much greater masses than other planets.
According to Space.com, the planets are the first of their kind to ever be discovered outside of our solar system. Closer to home, the ex-planet Pluto and its moon Charon are described as a binary system due to the fact that they each orbit a central point that is outside of each other’s boundaries. Each of the two newly discovered planets is thought to be between 200 and 300 million years old, and each has a mass roughly 15 times greater than Jupiter, but still small enough to be classified as planets.
The stars were discovered by Daniella Gagliuffi, a graduate student at the University of California, San Diego. According to Gagliuffi, the close proximity of the objects is unusual, making it likely that their orbits are entwined as a binary system:
They're probably brother and sister. It's a little incestuous. Given that they're so close, it's extremely likely that they're bound.
It’s this proximity to other stars that makes this pair of planets unique; usually, stars have a mass great enough to “lure” planets away from one another and begin orbiting stars. The two planets are found in a dense collection of stars, the closest to them being over ten times farther than Earth is from our Sun. Due to the abundance of nearby stars, it’s difficult to calculate the precise center of orbit for the twin planets.
There is a chance more data collection could reveal that the two planets orbit a distant star together. There is also chance that one or both of these two planets might be so-called brown dwarfs, which are essentially failed stars and technically not planets. If either of those scenarios turns out to be false, these planets could go down in history as the first known pair of binary exoplanets. Not a bad discovery for a graduate student.