Scientists have discovered that a distant world has a real rebellious character and outwardly challenges its red dwarf star. The extrasolar planet or exoplanet, called GJ 3090 b and located about 73 light years away, has a very misaligned orbit. In fact, it is spinning in the opposite direction to the rotation of its parent star. This is something scientists could explain if GJ 3090 b had a massive companion, whether a gas giant planet, brown dwarf, or another star. But it is not like that. No, this world, discovered in 2022, appears to be a unique one. “To our great surprise, the planet GJ 3090 b is not only in a very misaligned orbit, but also orbits retrogradely, in the opposite direction to the rotation of its star,” team member Yann Carteret of the Department of Astronomy at the University of Geneva (UNIGE) said in a statement. child stars. This matter rotates in the same direction as the young central star, which means that any planets that may arise should also rotate in the same direction. You may be interested Similarly, planets should also share an orbital plane similar to that of their parent star. The difference in orientation between the angular plane of a star and each of its planets is called Psi and arises as a result of perturbations during the planet formation phase. For example, the Earth’s Psi is 7 degrees. “Measuring the Psi angle provides clues about the formation and evolution of planetary systems. Therefore, it is natural that we try to measure it for other planetary systems,” Carteret said. GJ 3090 b has a radius 2.2 times that of Earth and a mass 4.5 times that of our planet, making it a “sub-Neptune.” Subneptunes are one of the most common planets in the Milky Way. However, when the team studied the world with the NIRPS instrument at the La Silla Observatory, this exoplanet seemed to possess something unusual: a Psi of 136 degrees. “It is the operation of the NIRPS in the infrared that made it possible to achieve the necessary precision to measure the angle between the orbital plane of the planet and the equatorial plane of the star for such a small planet,” said Léna Parc of UNIGE. A NASA model of exoplanet GJ 3090 b (Image credit: NASA) This planetary system is one of five ever seen with a Psi greater than 70 degrees, but what’s really different here is that those other systems possess a massive object that clearly appears to have caused the extremely misaligned orbits. “The absence of a massive companion to explain this unusual orbit will lead us to explore other hypotheses,” said Vincent Bourrier of UNIGE, also proposing an explanation for this massive Psi. “In the case of GJ 3090, the star could have accreted a misaligned and retrograde secondary disk in which the system’s planets later formed.” The team’s research was published Monday (September 21) in the journal Astronomy & Astrophysics.
