Previously Discovered Exoplanet Mysteriously Vanishes, Astronomers Figure It Out

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Fomalhaut b was always a strange occurrence. Announced in 2008, it was clearly visible in optical wavelengths; however, astronomers couldn't find the exoplanet's infrared signature that a planet of that size would create in the first place. It was for this reason that its legitimacy was always debated.

Never really a planet, it was just dust and light

A new paper argues that Fomalhaut b was never a planet at all.  Instead, it may have been the light from a massive collision between two asteroids or comets, or any other two large bodies. 

The reasoning behind their research was purely coincidental. According to András Gáspár, an astronomer at the University of Arizona and co-author of the paper, everything began after he downloaded Hubble's data to look at things that people might have missed in the past regarding Fomalhaut b.

The exoplanet was fading continually

What Gáspár saw was astonishing: Apparently, the alleged exoplanet’s light was fading and the exoplanet was vanishing over time. In the 2004 data where it was first imaged, the planet was bright and massive in optical wavelengths. However, ten years later, Hubble data shows the planet fading from sight.

This was the final nail in the coffin. According to Gaspar, "Our modeling shows the observed characteristics agree with a model of an expanding dust cloud produced in a massive collision."

An incredibly rare event

In the light of available data, the researchers think the collision occurred some time before the first discoveries in 2004. By now, the debris cloud, consisting of dust particles, has gone below Hubble's detection limit. 

According to the author’s calculations, the Fomalhaut system may experience one of these events only every 200,000 years.

"These collisions are exceedingly rare and so this is a big deal that we actually get to see one," says András Gáspár. "We believe that we were at the right place at the right time to have witnessed such an unlikely event with NASA's Hubble Space Telescope."

The research was published in the Journal Proceedings of the National Academy of Sciences.