‘Back from the dead': new analysis says exoplanet Fomalhaut b is real

Artist’s conception of Fomalhaut B. Credit: ESA / Hubble / M. Kornmesser / ESO / L. Calçada / L. L. Christensen

Among the many exoplanets now being discovered, Fomalhaut B was considered something special – the first exoplanet to be directly photographed in visible light, by the Hubble Space Telescope, back in 2008. That is, until more recent studies suggested that it might not be real, not even a planet after all.

It was photographed on the inside of a large ring of dust and debris surrounding its star, Fomalhaut, which is about 25 light-years away. The new studies implied that Fomalhaut B was actually just a cloud of dust, not a planet, due to the changing brightness of the object.

But now, there is another new analysis which brings Fomalhaut B back into the planetary family. According to Thayne Currie, an astronomer at the University of Toronto, “Although our results seriously challenge the original discovery paper, they do so in a way that actually makes the object’s interpretation much cleaner and leaves intact the core conclusion, that Fomalhaut b is indeed a massive planet.”

The data suggests that Fomalhaut B is indeed a large planet, more massive than Jupiter, but is surrounded by a cloud of dust. The result is sort of a compromise between the two differing sets of observations. The team re-analyzed Hubble data from 2004 and 2006 and found that the brightness was actually consistent.

“Given what we know about the behavior of dust and the environment where the planet is located, we think that we’re seeing a planetary object that is completely embedded in dust rather than a free-floating dust cloud,” said John Debes, an astronomer at the Space Telescope Science Institute.

The planet’s gravity also modifies and “sculpts” the dust and debris ring which surrounds the star. So while Fomalhaut B is itself surrounded by a cloud of dust, its orbit around the star also has an effect on this much larger ring.

Planets are thought to form from just such disks of dust and gas that surround new stars after they are born; Fomalhaut B may be a good example of seeing this actually happening – the development of a new planetary system.

As a result of the new study, the status of Fomalhaut B has also changed a bit, from a “directly imaged exoplanet” to a “planet identified from direct imaging,” a subtle but important distinction. As technology improves, however, other exoplanets are starting to also be photographed as well, although they are still just tiny dots of light.

The new findings are being published in The Astrophysical Journal Letters.

This article was first published on Examiner.com

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