Scientists Solve The Mystery Of The Disappearing Exoplanet Fomalhaut B

Astronomers thought they had discovered a new exoplanet about 25 light-years from Earth using Hubble Space Telescope data taken in 2004 and 2006. The scientists say that clearly visible in several years worth of Hubble observations was an object previously believed to be an exoplanet called Fomalhaut b. The object had been directly imaged but was quite different from other planets that had been discovered using Hubble raising mystery for astronomers.

Some of the mysteries about Fomalhaut b included that it was unusually bright in visible light and had no detectable infrared signature. Astronomers believe that the object isn't a planet after all, but the aftermath of a massive collision between two icy asteroid-sized bodies that collided while orbiting the star known as Fomalhaut. The astronomers now believe the added brightness came from a vast shell or ring of dust that encircles the object that could've been related to the collision.

The early Hubble observations also suggested that the object wasn't following an elliptical orbit as planets typically do. Instead, the object was on a hyperbolic path. One of the astronomers on the project says that collisions of this sort are exceedingly rare, and it's a big deal that scientists have been able to observe this one. The scientist says that "we were at the right place at the right time to have witnessed such an unlikely event with the Hubble Space Telescope."

Hubble images from 2014 showed that the object had vanished with earlier images showing that the object was fading over time. The scientists knew that Fomalhaut b wasn't behaving as a planet should. Astronomers believe that the collision between the two large bodies had occurred only shortly before Hubble made its first observations in 2004.

Currently, the debris cloud consists of dust particles that are around one micron and are too small to be detected by the Hubble space telescope. The team has determined the colliding bodies were likely a mixture of ice and dust, like the cometary bodies that exist in the Kuiper belt in the outer fringe of the solar system. The scientists estimate that the bodies were about 200 kilometers across.