After several years of research, an image from the ALMA observatory has offered compelling evidence that planets are beginning to form. While the child stars are still growing up

The photo from the Atacama Large Millimeter / submillimeter Array shows a young proto-stellar disk with multiple spaces and dust rings. This new result, just published in ‘Nature’, shows the youngest and most detailed example of rings of dust that act as cosmic cradles, where the seeds of the planets are formed and take hold.

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An international team of scientists led by Dominique Segura-Cox at the Max Planck Institute for Extraterrestrial Physics (MPE) in Germany targeted the protostar IRS 63 with the ALMA radio observatory. This system is 470 light years from Earth and is located deep within the dense interstellar cloud L1709 in the constellation of Ophiuchus. Protostars as young as IRS 63 are still enveloped in a large, massive layer of gas and dust called the envelope, and the protostar and disk feed on this reservoir of material.

In systems over a million years old, after protostars have finished gathering most of their mass, they have previously been detected dust rings in large quantities. IRS 63 is different: At less than 500,000 years old, it is less than half the age of other young stars with dust rings, and the protostar will continue to grow significantly in mass.

“The rings on the disk around IRS 63 are so young,” Segura-Cox emphasizes in a statement. “We used to think that the stars entered adulthood first and then they were the mothers of the planets that came later. But now we see that protostars and planets grow and evolve together from the earliest times, as brothers. “

Planets face serious obstacles during their early stages of formation. They have to grow from tiny dust particles, smaller than household dust here on Earth. “The rings on the IRS 63 disk are huge accumulations of dust, ready to combine into planets “, notes MPE co-author Anika Schmiedeke.

However, even after the dust piles up to form a planetary embryo, the planet that is still forming could disappear by spiraling inward and be consumed by the central protostar. If planets begin to form very early and at great distances from the protostar, they may better survive this process.

The team of researchers discovered that there are about 0.5 masses of Jupiter dust in the young disk of IRS 63 more than 20 astronomical units from its center (at a distance similar to the orbit of Uranus in our solar system). Not counting the amount of gas, which could add up to 100 times more material. It takes at least 0.03 Jupiter masses of solid material to form a planetary core that efficiently accumulates gas and grows to form a giant gaseous planet.

MPE team member Jaime Pineda adds: “These results show that we must focus on younger systems to truly understand planet formation“For example, there is growing evidence that Jupiter may have formed much further out in the Solar System, beyond Neptune’s orbit, and then migrate toward its current location. Similarly, the dust surrounding IRS 63 shows that there is enough material far from the protostar and at a young enough stage that there is a possibility that this Solar System analog will form planets in the way Jupiter is suspected to have formed.

“The size of the disk is very similar to that of our own Solar System,” explains Segura-Cox. “Even the mass of the protostar is slightly less than that of our Sun. Studying such young planet-forming disks around protostars can give us important knowledge about our own origins “, concludes.