The name of the planet is Tyche. The scientists are John Matese and Daniel Whitmire, from the University of Louisiana at Lafayette. According to them, this colossus is hiding in the Oort Cloud - the asteroid beehive that forms the outer shell of our solar system. They claim that data already captured by NASA's Wide-field Infrared Survey Explorer proves its existence. It only needs to be analyzed.
Matese and Whitmire are convinced that Tyche is very real now. 15,000 times farther from the Sun than Earth, Tyche would be made mostly of hydrogen and helium, the titanic planet would orbit the Sun with moons and rings around it, bubbling with clouds. It would even have a mild temperature (-73C) compared to the asteroids around it, which are almost near absolute zero.
But if you are waiting for a clear picture of it, don't hold your breath: Its existence would only be revealed over the next two years. [The Independent]
Original image by NASA is not a concept of Tyche - used to illustrate size.