‘Planet’ actually rare cosmic collision
A reanalysis of Hubble images reveals an ‘exoplanet’ to be a cloud of dust
What astronomers had previously thought to be an exoplanet might be something rarer – the remains of two comet-like objects which have crashed together.
The former planet, Fomalhaut b, was first announced in 2008 after four years of Hubble observations tracked a bright point moving through the planetary disc of a distant star. At the time, astronomers thought this was a newly formed exoplanet, making it the first one to be detected directly through visual observations. Researchers continued to observe the ‘planet’ every few years as it made its way around the star but were shocked in 2014 to discover that it had vanished.
After looking back at the last decade of observations, a team of exoplanet astronomers realised that Fomalhaut b had actually been fading for several years. They now believe that rather than being a full-fledged planet, Fomalhaut b is actually a cloud of dust created by the collision of two icy objects similar to those found in our Kuiper belt. “These collisions are exceedingly rare and so this is a big deal that we get to see evidence of one,” says Andras Gaspar from the University of Arizona’s Steward Observatory, who led the research.
Astronomers will continue to watch the system to gain an insight into how such cosmic crashes affect the evolution of growing planets.
“We do have evidence of such collisions in other systems, but none of this magnitude has been observed in our Solar System,” says the Steward Observatory’s George Rieke. “This is the blueprint of how planets destroy each other.” www.hubblesite.org