A Star is Born: The Life Cycle of Stars
By Valeria Moreno Lopez, age 16
Every single birth of a star in the sky begins in an immense cloud of gas, dust, and debris. These colorful clouds are called nebulae, cosmic wonders that swirl around space undisturbed for millions of years.
In the beginning stages of a star’s formation, many occurrences in space can cause a nebula to warp and change its structure. As a result, it will collapse on its own gravity, shrink, and spin faster until it leaves a hot and bright core called a protostar. After the young star is formed, it cannot be seen immediately due to debris surrounding it. Thousands of years later, the star will be able to gather enough heat to engulf anything around it. Finally, when temperatures reach about 27 million degrees, the atoms at the core stick together to emit huge amounts of energy. Thus, lighting the star.
Often, stars are categorized by their mass: lightweight, middleweight, or heavyweight. When gravity pulls towards the center of the star and gas pressure pushes out to the surface, it creates a balance and the star is stable throughout its life. Once the star is at the end of its life and gravity takes over, what happens then depends solely on its mass.
Lightweight stars, like our sun, can stay in their stable form for billions of years. After their fuel runs out they turn into red giants, large and red stars with low temperatures. Millions of years later, the outer layers of the giant will separate to become a planetary nebula. All that will be left is a white dwarf star the size of Earth, compressed by gravity. The white dwarf star will continue to float in space by itself for millions of years, until it cools down completely. It enters its final stage as a faded black star, emitting no light and floating in space by itself for the rest of time.
Middleweight stars evolve faster than lightweight stars, barely reaching a billion years in their stable form. Once their fuel runs out, they become bright supergiants. Their downfall is when a star explodes in a supernova and pushes the outer layers away from the star. All that is left is a small neutron core. Neutron stars are very dense, and about six miles in diameter. Being small in size with a greater mass creates pressure, and forces the star to spin very fast, nearly 50 times per second. This creates a magnetic field around the neutron star.
Heavyweight stars consume energy even faster, and turn into blue supergiants as soon as they are unstable. Blue stars signify they are hotter in temperature. Then, they will follow the same process as middleweight stars by exploding in a supernova. Since the mass is so big, it cannot be supported in space and will collapse onto itself, creating a black hole. Knowing this, it is scary how many unspecified black holes there are in the universe.
Everything in the universe has a life cycle, even the diamonds in the sky. Stars have phenomenal births and deaths, with millions of years of life and changes in between. There are an infinite number of stars in the galaxies, including the hundreds and thousands of stars that are formed every year.
[Sources: Planetarium ; Image Credit: NASA ]
About the Author: Valeria Moreno Lopez is a junior at La Follette High School and has been working at SSFP since third grade. Valeria is interested in writing about historical events and the environment. In her free time, she enjoys cheerleading and playing soccer.