Life Cycle of Stars

Before a Star is Born

Before a star is born interstellar medium makes up space. Interstellar Medium is the material between the stars in space. Interstellar Interstellar Medium is made up of gas and dust. It's mostly gas, consisting of 75% hydrogen and 25% helium. ABout 15% of the Milky Way is made up of Interstellar Medium.

First Stage of a Stars Life Cycle: Nebula Stage

The first stage of a stars life cycle is being a Nebula, this is when elements such as hydrogen and helium. A Nebula is a big cloud of gas and dust. A star forms when the turbulence within the cloud give enough rise to the knots with enough mass so the gas and dust can collapse under its own gravitational attraction. During the time the cloud collapses the material in the center heats up. The nebula has a hot core at the center of the collapsing cloud this will sometimes become a real star.


Equilibrium is when the star is stable and the gas pressure pushing out from the star is equal with the gravity pulling atoms into the center. The two forces that balance in equilibrium gas pressure and gravity.

The Birth of a Star

After Equilibrium comes a process known as fusion, this is when two atoms combine to form a different atom. The cause of this process is starting is when equilibrium is reached.

Main Sequence

The most prominent elements during this stage are hydrogen and helium, during this phase the hydrogen will fuse into helium. How long the star is in this phase depends on how large it is.

Red Giant Phase

During this phase helium is the most present element. During this phase the helium will fuse into carbon, and gravity will keep contracting to maintain the equilibrium. The stars luminosity will become brighter while entering the next stage.

Death of the Star

The reason a star dies is because the there isn't anymore fuel to keep it going, so it collapses. The possible ways a star dies are either a white dwarf, nebula , and black hole. Before becoming a black hole the star will become a supernova which is when the burning of the carbon happens so fast and has so much energy that it explodes. A planetary nebula is when the star runs out of fuel and blows off its outer layers causing nebula rings around the star to form.

The Star's Light

A star become blue-shifted when the star is moving towards you, and a star becomes red-shifted when the star is moving away from you. A star's light is an example of the doppler effect because the brighter the star is the closer it is and the dimmer the star is the farther it is, which means there luminosities are at either higher of lower frequencies.

Origin of Elements

Many elements come from star's, from the fusing of previous elements created before them.