Dragon Cloud reveals the secret of the birth of the Galaxy’s biggest stars

Scientists have investigated a giant gas-dust nebula known as the Dragon Cloud. A giant star is forming in it. This is a rare opportunity to see how the luminaries are born, the mass of which is ten times greater than the solar one.

Dragon Cloud.Source: NASA/ESA/STScI

How giant stars are born

Scientists have written thousands of articles about how giant stars die. The process of a supernova flare, which turns the remnants of a luminary into a black hole, is quite well studied. And the turbulent life of objects, the mass of which is dozens of times greater than the solar well described. It is clear that during their own existence they emit large masses of gas in the form of jets.

But the birth of these giants still contains a mystery. All stars are born in cold gas-dust clouds, the so-called stellar nurseries. And the initial stage of their formation is the contraction of a certain volume of matter from them. 

However, as the gas is contracted, it heats up. And heating causes the reverse process – expansion. There is a kind of physical swing that tears the gas clot to pieces. Therefore, they cannot be too big.

Two theories of the formation of giant stars

The question arises: how then should stars be formed which have a mass 40, 50 or even 80 times greater than the solar one? There are two different theories on this. The first of them is that they are formed by a happy coincidence.

Sometimes the processes in the gas-dust cloud are formed in such a way that part of it begins to shrink very quickly and does not have time to warm up. The consequence of this is one giant flare, in which a star is born.

An alternative version, known as the core accretion theory, states that giant stars are born small. But a gas-dust condensation continues to exist around them, which gradually falls on them, as a result of which they grow rapidly. At the same time, neighboring star embryos remain without fuel and cannot grow.

Dragon Cloud

Which of the two theories is correct, scientists still can not establish. Very giant stars are rare, and the process of their birth is extremely short by cosmic standards. The embryo of a giant star is an extremely rare phenomenon. That’s why scientists were so interested in finding such an object in a stellar nursery known as the Dragon Cloud.

It was possible to find it thanks to mapping this region of star formation, which is located 20 thousand light-years away from us. It was carried out using an array of ALMA antennas located in the Atacama Desert in Chile.

The Dragon Cloud is really a gigantic region containing 70 thousand stars such as the Sun. Inside it, the researchers found several areas with thickenings, inside which stars were born. But their attention was attracted by one giant. 

Subsequently, it turned out that it was still not one thickening, but two located next to each other. The first has a mass of 2 solar, and the second is 23 times more massive than our luminary. At the same time, they were stable and quiet, so there were no catastrophic processes around, contracting the gas at an incredible speed. 

Scientists realized that they were looking at an example of an accretion core. Soon a small star should be born inside, which will quickly begin to grow and in some million years will turn into an unusually bright and big giant.

According to www.space.com

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