Fomalhaut b
However, Fomalhaut b should be detectable in space-based infrared data if its mass is between 1-3 Jupiter masses. But sensitive infrared Spitzer Space Telescope observations failed to detect Fomalhaut b, implying that Fomalhaut b has less than 1 Jupiter mass. Furthermore, although the planet was thought to be a plausible explanation for Fomalhaut's eccentric debris ring, measurements in the Kalas et al. paper hinted that it was moving too fast (i.e. not apsidally aligned) for this explanation to work. Finally, researchers analyzing September–October 2011 Atacama Large Millimeter Array (ALMA) data for Fomalhaut's debris ring suggested an alternate hypothesis: that the ring could be shaped by much smaller, shepherding planets, neither of which needed to be Fomalhaut b. These results invoked skepticism about Fomalhaut b's status as an extrasolar planet.