Life Cycle of a Star

By: Taylor albright

Brife Summary of the Life Span of a Star and Human

Both a star and human start out as a fetus or a protostar. We then are born and mature from infancy through adulthood. A star then starts to produce two elements (hydrogen and helium) in its fusion ignition stage and matures into its main sequence. Our sun is in its main sequence. stars then turn into red giants or they can also be called Supergiant, much like our middle age. Humans then turn old and eventually die. A star matures into a white dwarf and then dies and turns into a black hole.
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Interstellar Medium

This is the matter that exists between the star systems in a galaxy. It's matter includes gas in ionic, atomic and molecular form, as well as dust.


Equilibrium- a state in which opposing forces or influences are balanced. The two different forces of and equilibrium is gravity and gas pressure. Gravity is caused by its own mass (pushes inward) and gas pressure is caused by heat (pushes outward).

The Birth of a Star

After the equilibrium is established the fusion proses begins. Tn this proses two main elements are made. (Hydrogen and Helium)

Main Sequence

In this phase it will start to burning Hydrogen and Helium. Increased temperature and density in the core reinitiates nuclear fusion, equilibrium is achieved, and then cycle begins again at step one.

Red Giant

In this phase hydrogen fuses into other elements like carbon and iron by nuclear fusion. A red giant lasts around 2.17 billion years after the end of the main sequence. When helium starts to burn this signifies the end of the red giant phase.

White Dwarf

The major elements in a white dwarf are carbon and oxygen. There is no nuclear fusion in the white dwarf phase. A white dwarf is very bright (luminosity) and its temperature is very high. Once the white dwarf phase is over the dying star can become a black hole or supernova.

Stars Light

A stars light can tell what stage its on main sequence, red giant, or white dwarf. By making observations of the light that a star gives off, or the light that is reflected from a planet, scientists can find out a lot of information about a distant star. This helps find the red shift. To use the doppler effect, the wave nature of light means there will be a shift in the spectral lines of an object if it is moving.

Origin of the Elements

Elements come from stars, starting with helium and hydrogen the the main sequence and witch then form into more elements like copper and iron during the red giant phase.

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