The BIRTH of a Star A star is

The BIRTH of a Star A star is born when gas and dust particles come together and make a cloud, called a Nebula. Gravity starts to compress the cloud, forcing the atoms to move closer. This starts a process called fusion. Fusion occurs when the atoms are so close together that they start to combine, making helium from hydrogen. When this happens, energy is created and a new star is formed!

The LIFE of a Star The length of a star’s life is determined by its mass. A star with a small mass will live longer than a star with a large mass because it burns less gas. The temperature of a star determines its color. The hottest stars are blue or white and the coolest stars are red or yellow. As a star goes through its life, it continues to fuse hydrogen molecules into helium molecules for fuel. As these molecules run out the star grows dimmer.

The DEATH of a Star A star dies when it runs out of hydrogen molecules which it uses for fuel. When this happens, the star can no longer hold up its mass, and it begins to collapse. Depending on the mass of the star, it dies a different death. Larger stars die violently, with a giant explosion. After the explosion, a small portion of the star is left behind to begin again. Smaller stars die peacefully and turn into Brown Dwarfs.

BINARY Stars Binary stars are a group of two or three stars that orbit around each other at a close distance. The group of stars rotate around a common center of mass. An example of this is the north star, Polaris.

WHITE DWARF White Dwarfs are formed when smaller stars die. They are the hottest of all dwarf stars. We know this because of their white color. When our sun dies in about a billion years, it will become a white dwarf.

BLACK DWARF A black dwarf is a star that has completely run out of hydrogen molecules. Black dwarfs do not exist in our galaxy yet, because it is not old enough. Computer simulations have told us that they will exist billions of years from now.

RED GIANT Red giants are large, and relatively cool, stars. They occur after a mediumlarge star collapses. After a star (like our sun) dies, it temporarily swells in size and then cools, before becoming a white dwarf.

SUPERGIANT Supergiants are the largest and brightest stars in the galaxy. Red supergiants are larger than blue ones, but less hot. When a large star runs out of hydrogen to fuse, it expands to become a red giant. When it reaches the stage of burning helium to carbon, it expands and become a red supergiant. Through strong winds, red supergiants are changed into a smaller and hotter blue supergiants.

SUPERNOVA The explosion called a supernova occurs after a large star has become a red supergiant. When the star stops expanding because it can no longer create enough energy to support its own mass, it collapses completely and makes a giant explosion. A supernova is brighter than all the stars in the galaxy combined! The energy created by the explosion can travel at a speed of a thousand miles per second. Supernovas also help to create other stars.

NEUTRON Star Neutron stars are created in the last phase of a mediumlarge star’s death. They are mostly made up of the center of atoms and are very dense. Neutron stars do not become a black hole because they do not have enough mass.

BLACK HOLES After a supernova explosion, a black hole is created. The remains of the star creates an object so dense that the force of gravity traps everything that comes near them. Even light cannot escape the black hole’s gravity. This is why it is black.