Birth:
Emerging from a cloud of gas and dust called a nebula, a star forms when gravity pulls hydrogen gas from the nebula together and spins it around at such a fast rate that it heats up. This creates what is known as a “protostar”. Once the soon-to-be star’s temperature reaches a point of 15 million degrees, nuclear fusion occurs, the protostar becomes stabilized, and then it becomes a star.
Mid-Life:
As the star shines on throughout its life, nuclear fusion continues to occur and the element hydrogen, that is found in its core, is constantly being converted to helium, which is then converted into heavier elements. The star continues to use nuclear fusion to transform lighter elements into heavier ones until a star reaches the element iron, where the energy required to produce a larger mass is too great.
Old Age:
As the star’s core runs out of hydrogen, the star stops producing heat through nuclear fusion and the core becomes unstable. The star’s outside shell (primarily composed of hydrogen) expands and begins to glow red. This phase is appropriately named the “red giant phase” because the star turns red as it cools off and it becomes a giant due to its expansion. At this point, all helium at the core of the red giant is transformed into carbon.
Death:
Stars with low mass, like our sun, will not turn into a supernova or a black hole. Instead, their core will collapse after all of its helium has been transformed into carbon. Ultimately the outer layers of the star are expelled and the core turns into a white dwarf, which eventually becomes a black dwarf once it cools.
