The Life Cycle of a Star By Scott Carlyle

Neutron Star or Black Hole Stage: Neutron Star or Black Hole Stage: If the star is a supergiant, it does not become a white dwarf, but instead forms a neutron star or a black hole. Main Sequence Stage: Within a million years, the baby star moves into its main sequence phase. Overview Star Formation: Star Formation: A star begins its life deep in a cloud of gases known as a nebula. White Dwarf and Black Dwarf Stage: Eventually, if the star is a red giant, it will collapse into a white dwarf. Red Giant or Supergiant Stage: Red Giant or Supergiant Stage: When the main sequence stage ends, the star enters the red giant or supergiant stage.

Star Formation  A star begins its life deep in a cloud of gases known as a nebula. Compression waves traveling through the nebula cause some of the gas particles to draw together into a knot. This knot of very compressed particles develops an internal temperature of several million degrees, and the intense heat causes fusion, in which the nuclei of adjacent particles actually fuse, releasing massive amounts of nuclear energy. The tightly packed core exerts a very strong gravitational force. Overview

Main Sequence Stage  Within a million years, the baby star moves into its main sequence phase. In this phase, the star loses some of its youthful brilliance when its own gravitational pull actually makes it shrink a little. Now the star settles into its job for the next 10 billion years: to slowly burn up its own supply of hydrogen. Overview

Red Giant or Supergiant Stage  When the main sequence stage ends, the star enters the red giant or supergiant stage. Its own gravitational force causes its core to contract and the hydrogen inside to be converted into helium, which expands outward from the shrinking core. The helium pushes against the outer layers of the star, and the star grows into a red giant. If the star is very massive, it may become a supergiant. Overview

White Dwarf and Black Dwarf Stage  Eventually, if the star is a red giant, it will collapse into a white dwarf. As a white dwarf, the star is much smaller, probably about the size of a planet such as Earth. Initially, the star continues to burn with a dull white color, but it also begins to cool. As it cools, it gets darker and darker until it completely loses its energy and becomes a black dwarf. Overview

Neutron Star or Black Hole Stage  If the star is a supergiant, it does not become a white dwarf, but instead forms a neutron star or a black hole. Like a red giant, a supergiant eventually begins to collapse, but with the star’s additional mass, its core becomes so condensed that its nuclei combine to form neutrons. The star then stabilizes as a neutron star. If the star is one of the largest supergiants, it will collapse even further into the densest space in the universe: a black hole. Overview