The researchers used the Subaru telescope near the top of an inactive Hawaiian volcano and the Hubble Space Telescope to detect and study the planet, a gas giant that orbits unusually far from its young star. Gas giants are planets, such as the largest in our solar system, Jupiter and Saturn, which consist mainly of hydrogen and helium, with swirling gases surrounding a smaller solid nucleus. “We believe it is still very early in the birth process,” said astrophysicist Thayne Currie of the Subaru Telescope and NASA-Ames Research Center, lead author of the study, which was published Monday in the journal Nature Astronomy. “Evidence shows that this is the oldest formation stage ever observed for a gas giant.”
9.5 trillion kilometers from Earth
It is embedded in an extensive disk of gas and dust, carrying planet-forming material that surrounds a star called AB Aurigae located 508 light-years – the distance light travels in one year, 9.5 trillion kilometers – from Earth. This star gained a fleeting moment of fame when his image appeared on a stage in the 2021 movie “Don’t Look Up”. About 5,000 planets, or extraterrestrials, have been identified beyond our solar system. This one, called AB Aur b, is one of the largest. Approaching the maximum size that should be classified as a planet and not as a brown dwarf, a body in between a planet and a star. It is heated by gas and dust that falls into it. Planets in the process of formation – called protoplanets – have been observed around just one other star. Almost all known exoplanets have orbits around their stars within the distance that separates our sun and the most distant planet of Poseidon. But this planet orbits three times farther from Poseidon than the sun and 93 times the distance of the Earth from the sun. His birth seems to follow a different process from the typical planetary formation model.
“Discovery challenges our understanding”
“The conventional thinking is that most – if not all – of the planets form by slowly accumulating solids in a rocky core, and that gas giants go through this phase before the solid nucleus becomes massive enough to start accumulating gas,” the astronomer said. and study partner. -author Olivier Guyon of the Subaru Telescope and the University of Arizona. In this scenario, the protoplanets embedded in the disk surrounding a young star gradually grow from dust into solid boulder-sized objects, and if this nucleus reaches the Earth’s mass many times, then they begin to accumulate gas from the disk. “This process cannot form giant planets at great orbital distances, so this discovery calls into question our understanding of planet formation,” Guyon said. Instead, researchers believe that AB Aur b is formed in a scenario in which the disk around the star cools and gravity causes it to fragment into one or more massive clusters formed on planets. “There is more than one way to cook an egg,” Currie said. “And obviously there can be more than one way to form a planet like Jupiter.” The star AB Aurigae is about 2.4 times more massive than our sun and almost 60 times brighter. It is about 2 million years old – an infant by astronomical standards – compared to about 4.5 billion years for our middle-aged sun. The sun early in his life was also surrounded by a disk that created the Earth and the other planets. “New astronomical observations are constantly challenging our current theories, ultimately improving our understanding of the universe,” Guyon said. “The formation of the planet is very complicated and messy, with many surprises still ahead.”
