Birth Of A Start Cont. Protostar very unstable In order to become a star must reach equilibrium Process called accretion http://www.youtube.com/watch?v=YU6X3SPZAJo
Types of Stars Protostar- The beginning stages of a star. Giant ball of gas. Stage lasts around 10,000 Years Main Sequence Star- Majority of the stars in our galaxy and universe. Vary in size and brightness. Fusion from the hydrogen fuel produces an outward force that counter-acts gravity’s inward force and creates Hydrostatic Equilibrium. Examples are our Sun, Sirius, and Alpha Centauri
Types of Stars Cont. Red Giant- Star has consumed its stock of hydrogen. Fusion stops. No outward pressure to counteract the inward pressure from gravity. Surface ignites continuing the life of the star but also making it grow up to 100x in size. Lasts only a few hundred million years. White Dwarf- Star has run out of hydrogen fuel for its core. The outward light pressure from the fusion reaction stops and the star collapses inward under its own gravity. It shines but has no fusion reaction.
Types of Stars Cont. Red Dwarf Stars- Most common kind of star. They have a low mass so it is cooler than our sun. They are able to keep the hydrogen fuel mixing in the core so they last longer than most stars. Last for about 10 trillion years. Super Giant- The largest of the stars. Consume hydrogen at fast rates. They live fast and die young. They are very unstable.
When a Star Dies Once a star has consumed all its hydrogen in its core, it dies. The smaller and Main Sequence stars turn into a White Dwarf Star and eventually into a Black Dwarf.
When a Star Dies Cont. When a Super Giant dies, a Supernova occurs. From there they can change into a Neutron Star or become a Black Hole. Neutron Star- After a Supergiant has used up all its hydrogen fuel, it dies in a Supernova. During the Supernova the intense force of gravity crushes all the protons and neutrons and creates a star completely made up of neutrons.
When a Star Dies Cont. Black Hole- A black hole is formed when a star of sufficient mass undergoes gravitational collapse, with most or all of its mass compressed into a sufficiently small area of space, causing infinite spacetime curvature at that point. Such a massive spacetime curvature allows nothing, not even light, to escape from the "event horizon," or border. (taken from about.physics.com) Black Holes have never been physically observed.