22 Cards in this Set
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Luminosity
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The total power output of an object, usually measured in watts or in units of solar luminosities (LSun �� 3.8 * 1026 watts).
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Coronal Mass Ejection
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Bursts of charged particles from the Sun’s corona that travel outward into space.
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Solar Wind
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A stream of charged particles ejected from the Sun.
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Sunspot
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Blotches on the surface of the Sun that appear darker than surrounding regions.
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Solar Flare
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Huge and sudden releases of energy on the solar surface, probably caused when energy stored in magnetic fields is suddenly released.
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Maunder minimum
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Astronomers observed virtually no sunspots between the 1645 and 1715
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Solar Prominence
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Vaulted loops of hot gas that rise above the Sun’s surface and follow magnetic field lines.
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Nuclear Fusion
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The process in which two (or more) smaller nuclei slam together and make one larger nucleus
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Nuclear Fission
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The process in which a larger nucleus splits into two (or more) smaller particles.
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Neutrino
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A type of fundamental particle that has extremely low mass and responds only to the weak force;
Essentially anti-matter.
Released during Nuclear fusion
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Gamma ray
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Light with very short wavelengths (and hence high frequencies)—shorter than those of X rays.
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Apparent brightness
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The amount of light reaching us per unit area from a luminous object; often measured in units of watts/m2.
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Parallax
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The apparent shifting of an object against the background, due to viewing it from different positions.
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H-R Diagram
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Hertzsprung-Russell (H-R) diagram A graph plotting individual stars as points, with stellar luminosity on the vertical axis and spectral type (or surface temperature) on the horizontal axis.
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Main-Sequence star
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(luminosity class V)
Stars whose temperature and luminosity place them on the main sequence of the H-R diagram. Main-sequence stars are all releasing energy by fusing hydrogen into helium in their cores.
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Giant star
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luminosity class III : Stars that appear just below the supergiants on the H-R diagram because they are somewhat smaller in radius and lower in luminosity.
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Supergiant
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The very large and very bright stars (luminosity class I) that appear at the top of an H-R diagram.
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Spectral type
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A way of classifying a star by the lines that appear in its spectrum; it is related to surface temperature. The basic spectral types are designated by a letter (OBAFGKM, with O for the hottest stars and M for the coolest) and are subdivided with numbers from 0 through 9.
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Parsec
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(pc) The distance to an object with a parallax angle of 1 arcsecond; approximately equal to 3.26 light-years.
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White Dwarf
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The hot, compact corpses of low-mass stars, typically with a mass similar to that of the Sun compressed to a volume the size of Earth.
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Open Cluster
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A cluster of up to several thousand
stars; open clusters are found only in the disks of galaxies and often contain young stars.
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Globular Cluster
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A spherically shaped cluster of up to a million or more stars; globular clusters are found primarily in the halos of galaxies and contain only very old stars.
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ASTR 1020: STUDY GUIDE