Why Are Stages of Stars Important?

The Life Cycle of Stars

• The stages in the life cycle of stars explain the stars' transformation throughout time. Stars are born out of clouds of degrading interstellar gas and dust. They then begin life as either sun-like stars or huge and giant stars. Sun-like stars become red giants while huge and giant stars become red supergiants. In the next stage red giants form, followed by planetary nebulas and supernovas. Planetary nebulas become white then black dwarfs. Supernovas become neutron stars and black holes.

Age of Galaxy

• The stage of a star can indicate the age of the galaxy it's contained within. The remaining supply of hydrogen that a star contains and how that star uses it determines its longevity. Red dwarfs have high longevity and are the most common star because they conserve hydrogen well in their cores. Conversely, supergiants are the largest stars, using up all their hydrogen fuel in a few million years. Stars that spin more slowly live longer but burn less brightly, while stars that spin more quickly live a shorter duration but burn brighter due to excessive fuel consumption.

Our Sun

• Stars also provide parallels with the sun, the most important star in our solar system. Stars similar to the sun indicate the age of the sun through the interpretation of their own hydrogen reserves. These stars, including the sun, have a lifespan of about 10 billion years. Understanding certain behaviors of the sun, such as solar flares, can even prevent possible dangers to people on earth. Currently, the sun is in its dormant stage, the next stage being the red giant stage, the last before it becomes a white dwarf.

Acceleration of the Universe

• The stages of stars illuminated the expansion of the universe. Astronomers once believed gravity was causing the universe to slow down. They needed to accurately measure the distance of stars from Earth. Eventually, they discovered the type of supernova that maintained a consistent relation between its brightness and age. It's formed from the explosion of a white dwarf, which has consistent mass and thus consistent peak luminosity. As a result, astronomers used this supernova as a standard candle or benchmark by which to measure distance in space. They discovered the universe was in fact accelerating, causing the universe to be flat.