“Fluffy” motes grow into children's planets

“Fluffy” motes grow into children's planets

The most powerful observatory in the world of radio is spying on fluffy microscopic dust particles that form constituent elements around a young star.

How is the children's planet formed? It would seem the answer is simple. Take a huge amount of dust in the orbit of a young star, squeeze it and - voila! - get the seed of a newborn planet, around which gravity attracts more and more material, creating a full-scale protoplanet.

Although from a logical point of view, everything is true, but many mysteries remain. Astronomers are still not sure how circumstellar gas and dust form planets. This question is a perennial mystery underlying the planetary model of formation, but we are close to some clues.

Now the largest radio observatory is studying the light coming from a young star to understand the formation process.

The Atakamsky large (antenna) millimeter-range (ALMA) array in Chile was used to study a certain type of polarization of radio waves coming from the 5 million-year-old star HD 142527. It has a weight of about 2 times the solar and located 500 light years from Earth, possesses a ring of dust and gas. Astronomers believe that they form the building blocks of the planetary system. But the mystery is how this dust will turn from microscopic specks into huge rocky planets thousands of miles in size.

“Fluffy” motes grow into children's planets

ALMA watches dust ring around HD 142527

Since dust grains are mostly the seeds of future exoplanets, Akimas Kataoka of the University of Heidelberg and the National Astronomical Observatory of Japan and his team used ALMA precision instruments to study the orientation and polarization of radio waves coming from the ring.

Radio waves are emitted by stars, and then dispersed as particles in a ring. Particle information is like a “fingerprint”. Kataoka was able to discern the size of the particles and came across a surprise: the individual particles were much smaller than expected in previous studies. It turns out that the main dust grains from which the planets will be formed occupy only 150 micrometers in width. This is about 2 times less than a grain of table salt and 10 times less than expectations.

This creates a problem with previous models of formation and only ignites the interest of scientists.

“Fluffy” motes grow into children's planets

The dust particles forming the elements for the formation of the planets are not simple particles, but complex structures consisting of many small dust particles.

New research shows that these are not simple spherical particles, but “fluffy”. That is, many small particles stick together and form more complex objects. Therefore, the previously discovered larger particles are clusters of small ones. And the mechanism by which this happens could become the main mechanism in the process of the birth of the planet. “Thanks to the high sensitivity of ALMA, we detected a tiny signal and got information about the shape of the dust particles,” said Kataoka. “This was the first step in researching the evolution of dust with polarimetry. I think that much more surprising is waiting for us further. ”

According to an early Kataoka study, these “fluffy dusty aggregates” are formed after compression by pressure from the radiation of a young star. In the end, they become so massive that they attract more material with their gravity and create the "seeds" of the planets.

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