Life Cycle of ... Stars!
Hello Astronomy Lovers, This month's blog post will be about the life cycle of stars! Almost everyone knows the life cycle of humans and animals, but most people don't even know that there is a life cycle for stars! Today, we will be learning more about the process in which a star is firstborn, how it carries its life, and how it ultimately dies and gives way to more stars just like itself! We will also be diving into our own sun and see how its fate will turn out too! If you are ready to learn about one of the many wonders of the universe, I am ready to input some knowledge into your brains! Let's just get into it!
What do I mean by the life cycle of stars?
To be honest, the life cycle of a star is almost the same as the life cycle of any human or animal in the world! A star is born, then it lives its life producing energy to its nearby planets or stars, then dies to make way for more stars just like itself to form! To Understand more, we can dive deeper into understanding our own star, the sun, for some context. The sun what we call a main-sequence star, meaning it's in the middle of its life cycle. Main sequence stars do what the sun does, give off stable amounts of energy, and are overall in a stable place. We can use the sun to guide us through the life cycle of all different types of stars. But before we can go deeper, we should come from the very beginning.
The Very Beginning: The Formation of Stars
Stars are first created from something called a Supernova, in most cases. You might have seen these spectacular pictures of these colorful clouds of gas and dust, and they are indeed supernova! A star can also be formed from planetary nebulas. Here's a picture below.
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So what essentially happens is that because of gravity, these small dust and gas particles collide with each other to form something called a star. what defines a star is basically an object that has something called Stellar nucleosynthesis (nuclear fusion) going on inside, basically when protons and neutrons come together to form elements because of the extreme heat and pressure inside of a star. All-stars can be classified into 2 categories, and their fate can be mapped to this initial categorization. There are "low mass" stars, stars with the lowest possible mass to sufficiently trigger nuclear fusion. These stars range between the mass of at least 13 Jupiters or a bit more. This is exactly what the mass of our sun is about, meaning the giant our sun is, it's only the bottom level of stars! In the earliest eras of star formation, the gas that the stars used to form into stars was just hydrogen and helium. So, when stars form, their main source of fuel is either H or Hi. For "high mass" stars, the beginning formation process is almost the same, but certainly on a bigger, more massive scale.
The Middle Stages of a Star
For "low mass" stars, once a star is formed, its Hydrogen will start turning itself to Helium, and this process can take billions of years to complete. This is where our sun is right now, in the process of converting hydrogen to helium. Through the process, its relative size, temperature, and brightness or luminosity remain almost the same. One about 75% of the hydrogen is used up by the star, something happens and things really start to change. The sun's core begins to shrink, and this causes the remaining hydrogen to fuse even more to generate more helium. This produces an increase in energy, and thus the sun starts to expand, while the core starts the shrink even more. This then changes the star's color and size, which makes it enter a stage called the "Red Giant." Again here, the star can sustain itself for maybe a billion years. Then, after almost all of the hydrogen is used up, the star starts to do something called a "triple-alpha process" where the helium starts to get converted into other review metals, including carbon and even oxygen. For a "high mass" star, its life cycle is a bit more lengthy. After enough dust is collected to form, it becomes big, bright, blue, and extremely hot. Here's where pretty much all the similarities end between low mass stars and high mass stars. Where low mass stars live for billions of years, high mass stars only live for only tens of millions of years, since the fuel burns faster because of the bigger mass. High mass stars also burn Hydrogen to helium and after about 75% of the H atoms burn out, the core also starts to compress and its outer layers start to expand, much like the low mass stars. But then, the core starts to slowly burn Helium to Carbon, then after almo0st all of the Carbon burn out, it starts to turn into Oxygen, then Neon, then Silicon, then finally Iron. Here, since Iron is the heaviest element that can be fused inside of the star, it's kind of like the end fuel source of the star, there ends the fusion process, ending the middle stages of its life.
The End (Or the beginning of something cooler!)
Now, we get to the end of the life cycle. For low mass stars, the explosion ends in a "big" bang, or an explosion, creating a planetary nebula, which creates a large cloud of gas, dust, and other substances. This can be used to create more stars, just like itself. But, with the explosion, something else is made in its core. Something called a "White Darf" is formed, which is almost the same size as our earth, but kind of like a metal, with free-floating protons, neutrons, and electrons. Meanwhile, for high mass stars, there's also an explosion, but it's a huge explosion that creates something called a supernova. This can then be used to create other high mass stars. Here, 2 things can happen. If the original star has a huge mass, it will be made as a black hole. Learn more about it in my previous post on Black Holes! If the mass of the original star is less than the biggest mass stars but smaller than at least 8 solar masses, it will become a neutron star, which is a whole other world of weird physics and even worlds.
And basically, that's it, the life cycle of stars. It might sound a bit much and confusing, but it'll all make sense with a bit more knowledge of Astronomy and Physics, but that's pretty much all you need to know on the basics of the life cycle of stars. Here's a link to a video that's really helpful to kind of understand the subject a bit more.
Thank you very much for reading my post, and hope you have a great rest of your day!
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