(ORDO NEWS) — A swirling cloud of dust and gas over 530 light-years away is not just a noisy miracle. This is a new piece of the puzzle showing how planets grow from tiny grains to giant globes.
Astronomers have received new images of the protoplanetary disk in the near infrared region around the young star AB Aurigae. They show spiral disturbances, which, according to researchers, are caused by a planet arising from dust.
“At the early stage of planet formation, hydrodynamic modeling shows that the accretion process generates an internal and external spiral structure at the planet’s location due to Lindblad resonances caused by disk – planet interactions,” the researchers write in their article.
“Although this important step is well described in theory, observational data are rare and not completely convincing.”
The new shots are some of the best that we have observed during this process in action.
The formation of planets is a fascinating process. First, a star should form, spinning a giant disk of dust and gas around itself. When this happens, the remaining disk starts to stick together, forming pieces – asteroids, comets, dwarf planets and, of course, planets.
Firstly, tiny lumps of cold material combine electrostatic forces. Then, as these lumps increase in size, they begin to generate enough gravitational energy to attract more dust, creating a dense, compact object.
During this process, the orbits of dust particles around the forming planet are perturbed, and the shape of their orbits becomes elliptical, creating oscillations between their nearest and farthest point.
If this oscillation is a multiple of the particle’s orbital period, it creates a resonance called the Lindblad resonance, which should generate a spiral structure.
This resonance, astronomers believe, creates the spiral arms of massive galaxies. But that which is big in the Universe is often also small. We saw the same physics in the rings of Saturn, and it should be observed during the formation of the planets.
AB Aurigae is one of the closest stars of its kind – very young, she is less than 10 million years old, surrounded by a thick protoplanetary disk. In 2017, observations using the Atacama array (ALMA) revealed coarse spiral forms that could become the most sought-after signs of planet formation.
So, an international team of astronomers decided to take a closer look at the star. Using SPHERE equipment mounted on the Very Large Telescope in Chile, they performed high-contrast near-infrared observations of AB Aurigae in December 2019 and January 2020.
This led to the clearest star shots we have ever seen, capturing faint light from smaller particles of dust. And in combination with earlier ALMA data, they revealed an S-shaped disturbance in the protoplanetary disk, which is very similar to spiral waves propagating from the accreting protoplanet.
A protoplanet is formed at a distance approximately equivalent to the distance of Neptune from the Sun. Its exact size is difficult to measure, but is estimated to be approximately 4 to 13 times the mass of Jupiter.
This is not a fully confirmed result. But he points out that AB Aurigae is a promising candidate for subsequent observations with the more powerful telescopes that are currently under construction.
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