Approximately 25 light-years away from Earth, in the constellation Piscis Austrinus, exists an A-Type main-sequence star called Fomalhaut, and around it, astronomers discovered (and imaged) what seemed to be a massive planet that was designated Fomalhaut b. This world was one of the first exoplanets directly imaged by telescopes. Now, this planet has seemingly disappeared.
The more we explore the cosmos, the more we understand that there are thousands of exoplanets out there. In fact, based on our best estimates, there could be several billions of exoplanets in our galaxy alone.
So far, we’ve discovered (confirmed) the existence of 4,151 exoplanets, most of which were discovered indirectly when their orbit took them in front of their stars, causing a shadow to be cast as the exoplanets swung around it. Seeing exoplanets through a telescope is much more difficult, and to date, no more than 50 exoplanets have been seen directly through one.
Observing an exoplanet directly through a telescope was first accomplished in two discoveries announced together back in 2008. Various exoplanets were seen orbiting the star HR 8799. These exoplanets were observed thanks to the use of ground-based telescopes. However, just around the same time, astronomers spotted a distant alien world orbiting the star Fomalhaut, using the Hubble Space Telescope.
This planet was dubbed Fomalhaut b, and it seemed to be a truly gigantic alien world, potentially as big as three Jupiters combined. A solitary planet dancing around the star Fomalhaut was spotted by the Hubble Space Telescope. The discovery of the planet was presented in a study published in the journal Science where the alien world Fomalhaut b was described as a young planet, around three times the mass of Jupiter.
“Fomalhaut b is one of the most intriguing discoveries ever made with the Hubble Space Telescope,” Kalas explained.
However, Fomalhaut b has disappeared. Vanished. It’s nowhere to be seen. It’s as if the planet was never there. And a new study hints at just that.
A new paper published in the Journal Proceedings of the National Academy of Sciences argues that Fomalhaut b was never really a planet and may have instead have been the light from a massive collision between two larger bodies, most likely asteroids or comets.
Since its discovery, Fomaluaht b was a strange signal. In fact, although the planet appeared to be clearly visible in optical wavelengths, astronomers trying to confirm its existence could not find the exoplanet’s infrared signature that a planet of that size should create. Infrared Spitzer Space Telescope observations did not manage to detect Fomalhaut b, implying that Fomalhaut b has less than 1 Jupiter mass.
This has cast doubt over the years whether the planet exists in the first place.
This is why some have theories that Fomalhaut b was no more than dust-cloud or material that was captured from the huge disk of debris that exists around the star Fomalhaut.
András Gáspár, an astronomer at the University of Arizona and co-author on the new paper, explains that everything began after downloading Telescope Data and looking at things that people might have missed in the past around Fomalhaut b. And Gaspar found that the alleged exoplanet’s light was fading. Gáspár and his colleague George Rieke studied the Hubble data and eventually noticed that the exoplanet was vanishing over time. In the 2004 data, the planet appeared bright and massive in optical wavelengths, but ten years later, Hubble data shows the planet fading from sight.
“Our modeling shows the observed characteristics agree with a model of an expanding dust cloud produced in a massive collision,” concludes Gáspár.