[아하! 우주] Capture of a baby planet as a fetus… “Growth” by absorbing surrounding substances” (research)

▲ Credit: Hammond et al

We are all living things that started from a single cell. The fertilized egg formed by the meeting of egg and sperm is implanted, grows steadily, and comes out into the world 10 months later.

It is very small before being born this way, but it is the same with planets like Earth and Jupiter which gradually grows and becomes a full grown man. The earth we live on was formed from small pieces of material collected in a protoplanetary disk, a ring of gas and dust around the sun, when it was still a small star.

Of course, it is not possible to directly confirm this appearance going back 4.6 billion years, but scientists have confirmed the planetary hypothesis by identifying protoplanetary disks around many baby stars. Of course, it is not easy to observe baby stars formed in gas and dust nebulae, so capturing small protoplanets that are born in nearby protoplanetary disks is a formidable task for scientists.

A research team from Monash University in Australia discovered a small embryo-like protoplanet growing around one of the well-known protoplanetary disks, HD169142. HD169142 is not close to Earth, but is relatively easy to observe because the protoplanetary disk is at a downward angle when viewed from us.

Through observations, the research team discovered a ring-like gap in the orbit of Neptune in the solar system where the material of the protoplanetary disk thins out. These gaps are usually thought to be the result of material being absorbed by the growing protoplanet. On one side of the gap, the research team identified a small fetus-like mass seen by ultrasound. However, due to the low resolution, it was difficult to distinguish whether it was a real planet or a passing ball of gas.

So, over several years, the research team noticed that the Kepler planetary mass had movement. As a result, the clump not only rotates the small star, but also exerts a gravitational influence on the surrounding rings.

According to the team’s simulation model, this protoplanet is not a tiny embryo, but is already a planet as large as Jupiter and continues to grow by absorbing material from its surroundings. From the ultrasound image, it looks like a small nursery that has just been implanted, but it is actually a fetus that has grown significantly, entering the second half of pregnancy.

When HD169142, now a small star, reaches the point of becoming a normal star in the distant future, it releases strong energy and pushes out the surrounding gas, causing the protoplanetary disk to dissipate and the planet that grows in it emerges, forming a planetary. system. Of course, the planet currently being formed probably isn’t one.

This process is a fleeting moment for stars and planets that live for eons, but each process spans millions of years, making it impossible to observe each process from a single star. Instead, scientists study the process of star and planet formation by observing baby stars and protoplanetary disks in various stages.

And as telescopes and observing instruments develop, more detailed information pours in. HD169142 is an important observational target, and follow-up observations and research results are expected.

Gordon Jung Science Columnist


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