How is a star born?

Our sun was formed in a period of 30-50 million years, with the materials of a dead star. Most stars are formed inside a nebula, but through what does a star go before becoming a star?

Stage 1: Protostar

No nebulae have a uniform density. There always exist knots that are denser than other parts of nebulae. These knots tend to have a bigger gravitational force, and they absorb the matter near them. Slowly, they become denser and heavier, attracting more and more matter into them. After approx. 1 million years,  the knot transforms into a “cocoon”, called a globule – a thick, dark drop, with the diameter of 60.000 AU (8975880000000 km). Inside the cocoon, there is a warm mass with a size similar to the solar system, spinning and emitting infrareds. This mass is called a protostar.

Stage 2: Proplyd 

As the matter is attracted to the centre of the globule, this starts to flatten. 100.000 years after the protostar has been formed, the diameter of the protostar is shrinking to 1 AU ( 149,598,000 km ) and know is surrounded by an inflated “pancake” of gases and dust.  This pancake is called a proplyd and has a diameter of 100 AU ( 149,598,800,000,000 km). This proplyd is believed to be a newborn planetary system, where the gases and dust become planets that orbit the star.

Stage 3: T Tauri Star

After approx. 1 million years, the protostar that now has a diameter of only 3-4 of our suns become a T Tauri Star. T Tauri Stars are rotating very fast and have very big magnetic fields. As the star rotates, its magnetism attracts nearby gases and absorbs them along the lines of its magnetic field. This type of activity creates black spots on the surface of the star, but they are much bigger than the one on the surface of our sun.

Stage 4: Flow of bipolar molecules

Just like the T Tauri gets its gases from the disk that surrounds it,  so it expels them. The expelled mass can’t escape along the plan of the disk, being, in turn, deviated perpendicular along the axe of the rotation of the star, creating 2 fascicles jets called flow of bipolar molecules. The fascicles hit interstellar gases, and make them glow, creating glowing nebulae. The flux stage of the star is very short, having the duration of only 10.000 years. After 2-3 million years the star can begin in its core to fusion hydrogen. This is the moment that the star begins its life.


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