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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. |