Raphael Galicher, Christian Marois, Ben Zuckerman, Bruce Macintosh
The nature and even the existence of a putative planet-mass companion ("Fomalhaut b") to Fomalhaut has been debated since 2008. In the present paper we reanalyze the multi-epoch Hubble Space Telescope (HST) optical images on which the discovery claim was based. We confirm that the HST images do reveal an object in orbit around Fomalhaut but the detailed results from our analysis differ in some ways from previous discussions. In particular, we do not confirm flux variability over a two-year interval at 0.6-micron wavelength, we detect Fomalhaut b for the first time at the short wavelength of 0.43microns, we find that the HST image of Fomalhaut b at 0.8m icrons may be extended beyond the PSF, and we cannot determine from our astrometry if Fomalhaut b will cross or not the dust ring. The optical through mid-infrared spectral energy distribution (SED) of Fomalhaut b cannot be explained as due to direct or scattered radiation from a massive planet. We 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.
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http://arxiv.org/abs/1210.6745
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