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ES ASTRO 4
Chapter 4 Stars and Galaxies
| Term | Definition |
|---|---|
| Galaxy | A large group of stars, dust, and gas held together by gravity |
| Local Group | Galaxies near enough to each other that they exhibit a gravitational pull on each other |
| Cluster | Local groups near enough to each other to be considered neighbors |
| Doppler | The apparent shift in frequency of periodic motion due to the motion of the emitter, receiver, or both |
| Constellation | Pattern of stars in the sky |
| Absolute Magnitude | The actual luminosity of a star |
| Apparent Magnitude | The measure of the luminosity of a star from earth |
| Light Year | The distance light travels in a year |
| Photosphere | Lowest layer of Sun's atmosphere; from which light is given off |
| Chromosphere | Sun's atmosphere just beyond the photosphere |
| Corona | Outermost layer of the sun's atmosphere |
| Fusion | The joining of atomic nucleii to form a larger element |
| Sunspot | Region on the sun's surface which is cooler than surrounding surface |
| CME | A massive burst of stellar wind and other ejecta from a star |
| Prominence | A large, bright, gaseous feature extending outward from the Sun's surface, often in a loop shape |
| Solar Flare | A large explosion in the sun's atmosphere |
| Main Sequence | A continuous and distinctive band of stars that appears on plots of stellar color versus brightness |
| Nebula | A large cloud of gas and dust in space |
| Giant | An expanded version of a main sequence star; usually in the latter stages of a fusion sequence |
| White Dwarf | When a low-mass star fuses all of its helium into carbon |
| Supergiant | The result of a super-massive star expanding |
| Neutron Star | The collapsed core of a supernova |
| Black Hole | The collapse of a very massive neutron star results in this |
| Big Bang | One theory for the beginning of the universe. All matter came into being in an instant, and expanded out from a single point. |