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Star Cycle
| Term | Definition |
|---|---|
| Life Cycle of a Star | The sequence of changes that occur in a star as it ages. |
| Interstellar Medium | A thinly spread area of gas and dust. The gas is mostly Hydrogen. The dust is mostly Carbon and Silicon. |
| Nebula | Interstellar medium begins to collect into big clouds. The birthplace of stars, as stars are made of gas and dust. "Star nursery." |
| Protostar | Inside the nebula are regions of greater or lesser gravity, causing the gas and dust to pull together. As more atoms gather, their gravitational attraction increases. Not a very stable phase because many reactions are occurring within the protostar. |
| Equilibrium | A battle between gravity and gas pressure. Reactions within life cycle phases where gravity and gas pressure are constantly changing. Equilibrium is reached when both are equal. |
| Star | An extremely hot ball of gas, with hydrogen fusing into helium at its core. Spend most of their lives fusing hydrogen. When the hydrogen is used up, stars fuse helium and carbon. They are always trying to achieve Equilibrium. |
| Main Sequence | Stars live out most of their lives in this phase. Stars have achieved nuclear fusion. Stars stay at equilibrium. Stars radiate (shine) energy into space. |
| Red Giant | Phase after main sequence. Low mass and high mass main sequence stars progress to red giants. Outer gas layers in the star expand. As the star uses all its fuel its core shrinks. Red in color. High luminosity. |
| Planetary Nebula | Occurs at the end of a low-mass red giant's life. The outer layers of the star are expelled. The core is very hot and luminous. The outer shell appears as brightly colored gas clouds. |
| White Dwarf | Forms when a low mass star runs out of fuel. The core of a Planetary Nebula. Final stage in the cycle for low mass stars. Incredibly dense. Gravity is 350,000 times that of gravity on Earth. Will change colors as it cools. |
| Black Dwarf | End product of a white dwarf. The last stage of stellar evolution for low mass stars. No longer emits heat of light. No longer a star. |
| Red Super Giants | The same thing as a giant star only much bigger. As a star gets older, it begins to run out of fuel and expand. |
| Supernova | Last stage of a massive star's life. Occurs as the star runs out of nuclear fuel and some of its mass flows into its core. Core becomes so heavy that it cannot withstand its own gravitational force. The core collapses and results in a giant explosion. |
| Neutron Star | The core left behind after a Supernova. Very dense (1 tsp= 1 billion tons). Gravity is 2 billion times that of Earth's gravity. Gravity presses the material in on itself so tightly that protons and electrons combine to make neutrons. |
| Black Hole | Forms when very massive stars collapse at the end of their life cycle. A large area in space with a very strong gravitational pull. Nothing can escape, even light. |
| (H-R) Hertzsprung–Russell diagram | Plots each star on a graph and measures the stars magnitude (luminosity/brightness) against its temperature (color). |
| Luminosity | The amount of energy (light) a star emits. Brightness. |
| Absolute Magnitude | The measure of a star's brightness as if it were at a standard distance of exactly 10 parsecs (32.6 light years) from the observer. The sun has an absolute magnitude of 4.83. |
| Brightness | Brightness is luminosity. |
Created by:
jefisher