Sciences. The first moon-forming disk surrounding an exoplanet

Madrid, 22 (European Press)

The astronomical community unequivocally discovered, for the first time, the existence of a disk around a planet outside the solar system.

Observations made with the Atacama Large Millimeter/submillimeter Array (ALMA), of which the European Southern Observatory (ESO) is a partner, will shed new light on how moons and planets form in young star systems.

“Our work provides a clear revelation of a disk in which satellites can form,” says Myriam Benesti, a researcher at Grenoble University (France) and the University of Chile, who led this new research published this Tuesday. In “The Astrophysical Journal Letters”.

“Our ALMA observations were obtained with such remarkable accuracy that we were able to clearly determine that the disk is associated with the planet and were able to constrain its size for the first time,” he adds.

The disk in question, called the planetary disk, surrounds the exoplanet PDS 70c, one of two giant Jupiter-like planets orbiting a star roughly 400 light-years away. The astronomical community had previously discovered indications of a “moon-forming” disk around this exoplanet, but because they could not clearly distinguish the disk from its surroundings, they were unable to confirm their discovery yet.

In addition, with the help of ALMA, Benisty and his team discovered that the disk is roughly the same diameter as the distance between the Sun and Earth, and enough mass to form up to three moon-sized satellites.

But the findings aren’t just key to discovering how moons were formed. “These new observations are also very important for testing theories about planet formation that have not yet been confirmed,” says Jehan Bey, a researcher in the Earth and Planetary Laboratory at the Carnegie Institution for Science (US) and one of the study’s authors.

Planets form in dusty disks around young stars, making them boring holes as they swallow the material in that stellar disk that allows them to grow. In the process, the planet can acquire its own planetary disk, which contributes to the growth of the planet by regulating the amount of material falling on it. At the same time, gas and dust from the planet’s surrounding disk can coalesce into larger and larger bodies through multiple collisions, eventually giving birth to moons.

But the astronomical community still does not fully understand the details of these processes. “In short, it is not yet clear when, where and how planets and moons form,” explains Stefano Faccini, ESO Research Fellow, who was also involved in the research.

Only external objects are detected in the creation process

According to Miriam Kepler, a researcher at the Max Planck Institute for Astronomy (Germany) and one of the study’s co-authors, more than 4,000 exoplanets have been found so far, but all of them have been discovered in mature systems. “PDS 70b and PDS 70c, which form a system reminiscent of the pair of Jupiter and Saturn, are the only two exoplanets discovered so far that are still in the making,” says the researcher.

“Therefore, this system provides us with a unique opportunity to observe and study the processes of formation of planets and satellites,” adds Faccini.

PDS 70b and PDS 70c, the two planets that make up the system, were first discovered using ESO’s Very Large Telescope (VLT) in 2018 and 2019 respectively, and due to their unique nature they have been observed with other telescopes and instruments many times since then . and then.

Now, the latest high-resolution observations from ALMA have allowed the astronomical community to learn more about the system. Además de confirmar la detección del disco circumplanetario alrededor de PDS 70c y estudiar su tamaño y masa, descubrieron que PDS 70b no muestra evidencia clara de tener este tipo de disco, lo que indica que PDS 70c ma consumi en vor place of increase.

ESO’s Very Large Telescope (ELT), which is currently under construction in Cerro Armazones, in the Chilean Atacama Desert, will provide a deeper understanding of this planetary system: “ELT will be key to this research because, with much higher resolution, we will be able to map of the system in great detail,” says co-author Richard Teague, a researcher at the Center for Astrophysics.