For the first time, astronomers appear to have seen direct evidence of a planet forming around a young star . They have identified a spiral disk of gas and dust surrounding the star AB Aurigae that contains a small S-shaped spin near the center of the spiral, images from the infrared telescope show. That turn “is the precise place where a new planet must form,” says astrophysicist Emmanuel Di Folco of the University of Bordeaux in France, co-author of the work collected by the journal Astronomy & Astrophysics.
Previously, scientists had located large-scale spirals believed to have been created by invisible planets in disks of gas and dust around young stars. Theories about how planets merge and gather material from these disks predict that the movements of the planets would further spin the gas around them like spinning skirts, signaling the location of a planet.
Now, Di Folco and his colleagues have used infrared observations from the Atacama Large Millimeter / submillimeter Array and Very Large Telescope , both telescopes in Chile, to find a spiral and one of those S-shaped spins around AB Aurigae.
Impressive new images of the protoplanetary disk around the young star (about 520 light years distant in the constellation Auriga and only 4 million years old, one thousandth that of the Sun) show spiral disturbances that astronomers believe that are caused by planets that are created from dust.
“In the early stage of planet formation, hydrodynamic simulations indicate that the accretion process generates an internal and external spiral pattern at the planet site due to Lindblad resonances induced by disk-planet interactions,” the authors wrote. . “While this crucial step is well documented by theoretical work, observational evidence is rare and not entirely conclusive.”
The new images are some of the best we’ve seen so far of this process in action. It could be the first direct evidence of the formation of a baby planet.
If the planet is there, it would be as far from AB Aurigae as Neptune from the Sun, approximately 4.5 billion kilometers.
“We need to observe very young systems to really capture the moment when planets form,” lead author Anthony Boccaletti of the Observatoire de Paris said in a statement. “Thousands of exoplanets have been identified so far, but little is known about how they form.”
ALMA had seen the inner spiral arm, but thanks to the new observations, both the inner spiral and the spin have become visible, which is very important, as it corroborates some current ideas about how planets could be born.
“The spin arises in some theoretical models of planet formation,” said co-author Anne Dutrey. “It corresponds to the connection of two spirals, one that winds inward from the planet’s orbit and the other that expands outward, which come together at the location of the planet. They allow gas and dust from the disk to accumulate in the planet in formation and make it grow . “
ESO’s Extremely Large Telescope, the world’s largest “eye in the sky” , which is being built in Chile at the moment, will have the ability to see this system even more in depth and will be able to confirm if we are really seeing the existence of the birth of a planet.
The exact mass of the potential planet is not known, but it would probably have to be a gas giant like Jupiter rather than a rocky planet like Earth to make waves that large on the disk. And you may not be alone: there is a hint of another planet near the outer edge of the disk.
Referencia: Are we witnessing ongoing planet formation in AB Aurigae? A showcase of the SPHERE/ALMA synergy, Astronomy & Astrophysics (2020). www.aanda.org/10.1051/0004-6361/202038008
