In a preprint paper published today on the Los Alamos astro-ph website, astronomers have concluded that the exoplanet orbiting the star Formalhaut might not exist. This planet, the first exoplanet ever thought to be directly imaged in visible light, was first described in a paper published in 2008, and was actually tracked in its orbit over several years, as shown in the image on the right.

The new research used the Spitzer Space Telescope to see if the planet’s heat could be detected in infrared wavelengths. Unfortunately, the scientists found nothing.

No signature is found at the position where Fomalhaut b would be expected.

The scientists did detect another infrared source in a different location in the well-documented dust disk that surrounds Formalhaut, but even this had too weak a signal to be considered an actual planet. The scientists instead concluded that both their detection and the 2008 detection were instead short-lived clouds of dust that became visible when the orbiting dust became temporarily more concentrated, much like water clouds in our atmosphere will ebb and flow as they move through the sky.

Concerning the visible-light point source, its under-lying physics is unclear, but the only hypothesis that can be shown to reasonably fit all existing data is an optically thin dust cloud, which is transient or has a transient component.

What does this result mean for exoplanet research? It shows that even with all the recent exoplanet discoveries there remain many unknowns and uncertainties in this field. Scientists must remain vigilant and skeptical. What they think they might have found yesterday could prove ephemeral today.