By Kai Singh
Edited by Eman Hamed
The concept of space has been the root of many philosophical questions since the creation of cognitive thought, but tackling the entirety of space head-on is a dizzying and futile chore that will leave you more confused than enlightened. So, scientists have decided to take on space bit by bit, understanding more and more incrementally rather than all of it at once. One concept often studied are stars, which are hot balls of gas. Scientists work toward analyzing how stars are born, how they exist, and how to go about burning those that get too close for comfort.
To put it simply, stars are balls of gases that are held together by their own gravity (which is a natural phenomenon where the mass of an object creates a pull with other objects). There are 7 different types of stars that we know of and can study. These 7 are categorized as protostars, main sequence stars, neutron stars, red dwarf stars, white dwarf stars, red giants, and supergiant stars.
A protostar is what exists before a star forms, which is a collection of gas that has collapsed down from a giant molecular cloud. The protostar phase of stellar evolution lasts about 100,000 years. Over time, gravity and pressure increase, forcing the protostar to collapse down. All of the energy released by the protostar comes only from heating caused by the gravitational energy – A.K.A. nuclear fusion reactions that have not started yet.
There are about 100 billion stars in the Milky Way galaxy alone!
Main sequence stars are a majority of the stars that we are aware of, and they have one job: making tremendous amounts of energy by converting hydrogen into helium. The lower mass limit for a main sequence star is about 0.08 times the mass of the Sun, or 80 times the mass of Jupiter. Stars can theoretically grow to more than 100 times the mass of the Sun.
Red dwarf stars are the most common stars, but some of the coolest. Our sun falls into this category. These stars have the potential to live for trillions of years, as they can mix hydrogen in their core, allowing them to preserve it for a longer time.
A white dwarf is a star that no longer produces heat since it has no more elements to fuel it. This star still shines since it was once hot, but it will slowly start cooling down until it’s universe temperature. This takes about a hundred of billions of years though, so no star has fully cooled down yet.
When a star is approximately the size of our Sun, the star doesn’t make a white dwarf when it dies. Instead it supernovas, or explodes, and at the core forms a neutron star, or a star completely made of neutrons. If the star is any bigger, it can also make a black hole.
Red giants are stars that are in the elderly stage of stars. Stars feed off of hydrogen, and these stars form when their stockpile of hydrogen is over. They increase in size and get heavier and heavier, until they eventually become a white dwarf.
Lastly, supergiants are the biggest stars that we know about. These stars live fast and die young, as they are extremely unstable and consume a massive amount of hydrogen, making their life span only a few million years.
Space is infinite, and yet we are lucky to have the luxury of being able to look up at the night sky and see the other stars and planets glittering against the dark blue night. When we take into account how far away these stars are, we realize that the starlight we see at night is the light of stars that are already dead. So, the next time you look up into the sky, remember that the starlight you are under has travelled millions of light years to have been seen by you. If it can make its mark on the universe, so can you.