In the article “What is the life cycle of stars “by Universe Today, it talks about how the stars are formed, what happens to their lifetime, and how they eventually die. This relates to our 14th objective “I can understand how stars die and evolve”accordingly. We learned in class that all stars start out as clouds of cold molecular gas. The cloud could be in the galaxy for a long time before it starts to collapse down under its own gravity, when it collapses the cloud breaks down into smaller pieces. Once the smaller pieces collapse inward on themselves each one becomes a star. Then the cloud continues to collapse, the gravitational energy causes the star to heat up and the conservation of momentum from all of the individual particles causes the stars to start spinning. This is known as a protostar, their lifespan depends on the mass of the star. According to the article, for a star that has the same mass of our sun it last about 1 million years. Main sequence stars are stars that eventually reach the temperature to start fusion at its core, we learned this in our lecture tutorial. Main sequence stars go through this process when they “convert protons of hydrogen through several stages and two atoms of helium” this gives the star more heat than it requires. With the core having more things that it requires it releases huge amount of energy, it starts out as GammaRay’s but eventually it will turn into wavelength. The light of the star pushes outward and counteracts with the gravitational force pulling it in word at this point the stars life is held in balance as long as the hydrogen fuel doesn’t run out, that’s when the star will die. Main sequence stars also depend on the mass of the star on how long it’s lifespan will be. The HR diagram that we learned about in class also shows lifespan of main sequence stars. The largest stars have the shortest lives.
Red giants- convert hydrogen into helium, as the helium build up the high didn’t feel runs out and that’s when internal nuclear reaction stop. Without any light pressure going out like main sequence stars to star will be going to contract inward through gravity. According to the article, this process heats up a shell of hydrogen around the core which that ignites the fusion and causes the star to brighten up again. This also causes the stars outer layer to expand increasing the size of the star. Once the stars temperature and pressure of the core reaches the point that helium can be fused in the carbon it will break down and die, no longer being a red giant. They then can undergo a supernova explosion and leave behind a neutron star, if the star is big enough.The star can also implode to form an infinite gravitational warp in space, a black hole.
We learned that White Dwarf stars never reach nuclear fusion, so once it runs out of helium at its core is dead. Most low mass stars will turn into a white dwarf, large mass stars can turn into a neutron star, very large mass stars can turn into a supernova or black hole. This article was really interesting about how it’s different star goes through different stages to evolve into what it is. The article shows different examples of other stars and shows videos of the processes each star goes through.