Stars are large spheres or spheroids made of plasma, which is bound by the gravitational force of itself. Plasma is considered the fourth state of matter. It’s the fine point where an object is neither liquid, gas, nor solid. Effectively, we can categorise it as a state where excessive heat ionizes matter until it is a superheated and ionized gas. Stars are typically made of hydrogen and helium, the first 2 elements on the periodic table.

Stars are born in distant nebulae, often dubbed star nurseries. The nebulae are dense condensations of gases and stardust. When a heavy accumulation starts to form, they all generate a gravitational force, which starts to bind them. This process is extremely slow, and often takes millions of years. The accumulation of these masses then starts pulling in more gasses until a point where the compression causes the core to heat up. This ignites the star, and the gravitational force (which is spherical due to equality in all directions) traps the gasses. this creates a boiling spheroid of gasses. Most of the solid matter also burns off into gasses. 98% of most stars are made of hydrogen and helium. The remaining 2% is just other trace gasses.

There are multiple different types of stars in the universe. Let’s start with blue stars. Blue stars are fairly large and violent stars, which are rather hot. They are found in very complex systems and have very short lives due to constant mass transfer among stars, they have a shorter lifespan, and have violent conclusions, mostly ending in supernovae. They are known for their absorption of Helium-2.

Next are the red dwarf stars. Red dwarves are on the colder spectrum of stars in the universe, coincidentally the most common ones too. They have a special ability thanks to their temperature, the helium can stay away from the boiling core, allowing it to have a longer life. As the name suggests, they are rather tiny compared to other stars.

 Yellow dwarves occupy about 10% of the universe. They are some of the brightest stars, the glow a whiteish yellow. They have an average surface temperature of 6000 degrees Celsius. Our own sun is a yellow dwarf. Yellow dwarves turn into red giants as they run out of fuel.

 

 

Orange dwarves are great for life, as they emit less UV light than other stars. The light they emit is closer to neutral on the light spectrum. They are moderately common, which allows for life to be found better. Focussing the search on such stars would make finding exoplanets easier.

 

 

 Blue giants are next. They are one of the brightest stars in the universe. They usually move away from the denser areas where blue stars are formed and expand as they lose fuel and hence gain size as they lose gravitational pull.

 

Red giants are essentially dying red stars. Whatever helium it was running on dies out, and then the heat is passed on to the outer shell. The shell continues to burn, but the core loses gravity, causing the star to expand up to 100 times its original size.

White giants are stars that lose all their fuel. They collapse under whatever tiny quotients of gravity are holding the mass together. They glow for about a hundred million years, after which they just become the background temperature of the universe.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Neutron stars are probably the coolest type of stars. They are ones that continue to compress after they turn into white dwarves. This causes them to have exponentially large gravitational fields. This is because the compression converts electrons into neutrons, which carry no electrical charge.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Now let’s discuss the life cycle of stars. Stars can follow two paths. Either they can result into a sun like a star after its birth in a nebula, followed by turning into a red giant, turn into another nebula, and finally turn into a white dwarf. The other path is turning into an extremely large star, then a red supergiant, and then a supernova. A supernova is essentially a gigantic explosion of stars which spins very fast and travels around the universe. After that depending on its size, it either turns into a black hole or supernova.