Fomalhaut B - Recovery/independent Confirmation With Hubble and Further Controversy

Recovery/independent Confirmation With Hubble and Further Controversy

On October 24, 2012, a team lead by Thayne Currie at the University of Toronto announced the first independent recovery of Fomalhaut b and revived the claim that Fomalhaut b identifies a planet. They reanalyzed the original Hubble data using new, more powerful algorithms for separating planet light from starlight and confirmed that Fomalhaut b does exist. They also provided a new detection of Fomalhaut b at 0.4 µm.

Their analysis showed that Fomalhaut b was unlikely to have been detected in the infrared anyway and yielded a velocity for Fomalhaut b smaller than that derived in the discovery paper and consistent with that needed for Fomalhaut b to be a planet sculpting the debris ring. They consider Fomalhaut b to plausibly be a “planet identified from direct imaging” even if Fomalhaut b is not, strictly speaking, a directly-imaged planet.

A second paper made public later and lead by Raphael Galicher and Christian Marois at the Herzberg Institute for Astrophysics also independently recover Fomalhaut b and confirm the new 0.4 µm detection, claiming the spectral energy distribution (SED) of Fomalhaut b cannot be explained as due to direct or scattered radiation from a massive planet. They consider two models to explain the SED: (1) a large circumplanetary disk around a massive, but unseen, planet and (2) the aftermath of a collision during the past 100 years of two Kuiper Belt-like objects of radii about 50 km.

The revival of the claim that Fomalhaut b is (possibly) a planet after it had been discounted led some to nickname the object a “zombie planet”, although this is a non-technical term that does not appear in any paper. Of course, to be considered a planet in our Solar System, unlike Pluto, it would have to clear the neighborhood around its orbit.