How stars are formed?

Stars fill our sky with beauty and fascination. Have you ever wondered how stars are formed? Here is how.
A giant gas cloud called Nebulae
Stars are born from a large collection of cosmic dust called Nebulae. Nebulae are cool enough to form molecules. The denser regions of a Nebulae shrinks, forming what we call gas globules. Their formation is also accelerated by the materials injected and the pressure exerted by a nearby supernova explosion.
A Protostar is Born
As gas globules huddles up its core begins to heat up. More materials keep spiraling inwards ultimately forming what we call the Protostar. Protostars are often is the beginning surrounded by a disk of clouds composed of dust and gas.

For stars that share the same mass of Earth protostar phase would last approximately 100,000 years.

The T-Tauri Phase
Eventually, as the protostar matures, it generates energy winds that push the surrounding gas material away, allowing to observe the newborn star clearly.

Till here, all-stars grow up similarly. But depending on how much mass a protostar has acquired it goes on to become either a Brown Dwarf or enters into the Main Sequence phase of the star.

Brown Dwarfs do not reach stable luminosities as it does not achieve thermonuclear fusion of normal hydrogen. They produce energy by fusion of deuterium for the first few million years. They eventually stabilize and lead a calmer life.

Main Sequence Phase
This phase is where a star spends most of its life cycle.
In this phase, the star generates energy and light by the fusion reaction of hydrogen into helium.
The core of a star is very reactive here and the star keeps itself from not falling inwards by achieving something called hydrostatic equilibrium. Here the gravitational collapse is balanced out by the energy produced from the fusion reactions at the core.

How long the main sequence will last depends on the size of the star. Stars will larger mass than Sun ends up having a lot of mass to burn and as result, they burn faster. Our sun would last around 10 Billion years in this phase, while a star 10 times the sun will exit the phase in around 20 Million years.

Red Giant Expansion
After stars stop converting hydrogen into helium via nuclear fusion, gravity will take over.
The core cools down and collapses on itself to expand as Red Giants.
Red giant stars can reach enormous sizes ranging from 100 to 1,000 times the size of the sun today. Due to lower temperatures, they appear red in color.

Material Fusion
As the Red giants expand helium fusion controls the core from collapsing. When helium gets used up the star turns to use Carbon for fusion causing the core to shrink. This is continued until we are left with Iron. Iron fusion takes up a lot of energy and causes the core to collapse soon after.

Stars up to 8 times the size of the Sun shrinks to end up as peaceful white dwarfs eventually giving of their outer layers as Nebula feeders. Even smaller stars end their journey as red dwarfs.

Supernovae and Nebulae
When a star is sufficiently large enough, it ends up exploding violently. This explosion is called a Supernova. A Supernova explosion throws materials into space at speeds of 9,000 to 25,000 miles per second. These materials feed nebulae and aid the creation of new stars. Whatever remains after an explosion either shrinks itself to form a Black Hole or a Neutron star.

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