Scientists Have Discovered The Secret Of The Planet Dagon, Which Never Existed
The results of a study by American scientists suggest that one of the most famous exoplanets never existed, and the signal recorded by the Hubble space telescope from it was the result of the collision of two icy celestial bodies. An article about this is published in the journal Proceedings of the National Academy of Sciences.
The exoplanet Fomalhaut b was discovered by the Hubble telescope on November 13, 2008, at the very edge of the circumstellar disk of the star Fomalhaut in the constellation of southern Pisces, one of the brightest stars in the night sky. In 2011, the discovery was confirmed by ALMA project scientists working on a large complex of radio telescopes in the Atacama desert in Chile, who have already announced the discovery of two planets: Fomalhaut b and Fomalhaut c.
In 2015, Fomalhaut b, among other most famous exoplanets, received its name — Dagon, in honor of the Semitic deity. It was believed that this planet belongs to the class of gas giants and rotates around its star in a long elliptical orbit.
However, the analysis of later unpublished images of Hubble in 2014 did not just surprise scientists. They were startled because there was nothing where the planet should have been. It simply disappeared from Hubble's observations.
Scientists from the University of Arizona conducted a study and concluded that it is not a matter of changing the orbit. The authors believe that there was no exoplanet Dagon at all, and the bright spot that is visible in the early images of Hubble is the consequence of the collision of two planetesimals the size of an asteroid.
"These collisions are extremely rare, so, surprisingly, we were able to see this collision," the University's first author, astronomer Andras Gaspar, is quoted as saying in a press release. — We believe we were in the right place at the right time to witness such an unlikely event with the Hubble space telescope.
The identification of Dagon has always caused issues. Fomalhaut is a fairly young star, about 440 million years old, and it is still surrounded by an icy ring of dust and gas, the remnants of a circumstellar disk. This means that any planets orbiting the star must also be fairly young and therefore warm, emitting infrared radiation. However, no infrared radiation was detected on the planet Dagon. It was also too bright an object to be detected in visible light, which is extremely rare for exoplanets, which are usually too small to be observed directly.
To explain these features, scientists have previously assumed that the planet is shrouded in a huge ring or cloud of dust formed as a result of collisions with other objects or a smaller planet with a huge ring system. Some even considered Dagon a neutron star.
But none of these explanations were convincing. And there was another inexplicable problem: Dagon's orbit crossed the ring of debris around the star without breaking it gravitationally, as it should have been in the case of a planet. Therefore, astronomers continued to observe the system.
"Our study, which analyzed all available Hubble archive data on Fomalhaut b, including the most recent images, revealed several characteristics that together paint the picture that an object the size of a planet may never have existed at all," says Gaspar.
The results of the analysis of Hubble data in 2014 showed a huge expanding and gradually fading cloud of dust on the site of the planet Dagon, which probably arose as a result of a cosmic collision.
Scientists from the University of Arizona suggest that the collision occurred shortly before 2004 when the first image of Hubble was obtained. Each of the two colliding bodies, according to the authors, was an object about 200 kilometers across, consisting of rock and ice, like comets in the Solar system.