Stars are born in the Nebulae, Clouds of dust and gas mostly Hydrogen. Nebulae are of vast sizes, some are hundreds of light-years in diameter. Some nebulae are called “star nurseries”. By Observing Nebulaes in different stages of evolution, we can determine how Stars are born.
Birth of a Star
It all starts within a Nebula where clouds want to dissipate like smoke in the air and on the other hand gravity wants to pull it together. Gravity wins pulling in over the gas pressure pushing them out.
The material crunches down into the disc which is the beginning of becoming a star. This new star is called protostar.
It becomes denser and denser as gravity pulls more gas towards the center of this disc. Which makes it hotter.
This protostar becomes much hotter until the temperature reaches 18 million degrees. At this temperature, the disc undergoes a massive transformation. The Hydrogen atom fuses (Thermonuclear Fusion) together to form Helium and due to the nuclear energy obtained during this process, a Star finally shines.
The core of these newly born stars heats up thereby creating more nuclear energy which clears the surroundings over the next few million years.
The Stars are categorized based on several parameters like surface temperatures, amount of light they emit (luminosity), etc.
Death of a star
All stars burn through their hydrogen fuel and when they are out of fuel they die out.
Less massive stars like our sun release the stellar material into space forming a White Dwarf surrounded by Planetary Nebula.
More Massive stars blast’s matter into space in a bright supernova leaving behind extreme dense body called Neutron Star.
More Massive Stars at least three times the mass of our sun collapse into themselves leaving behind the dense remnant which turns into a Black Hole.