IB Physics: Astrophysics (Option E) – Flashcards
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Luminosity
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how bright a star will be in relation to the sun if all star were the same distance from the observer
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Light Year
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the distance light travels in one year
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Ellipse
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A elongated circle, or oval shape, the shape of the planets orbit.
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Astronomical Unit
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The average distance between Earth and the sun, about 150 million kilometers (1.5 x 10^11)
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Stellar Cluster
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A group of stars that are physically near each other in space, created by the collapse of the same gas cloud.
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Relative Density
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The density of a star or planet relative to another star or planet.
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Stefan - Boltzmann Law
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Total Energy Radiated per Unit Time (W) = Stefan - Boltzmann Constant 5.67 x 10^-8 (Wm^-2K^-4) x Surface Area of Body x Temperature of Black Body ^ 4
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Wien's Displacement Law
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Peak Wavelength (m) = (2.90 x 10^-3) / Distance from star to earth.
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Absorption Spectrum
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the spectrum of electromagnetic radiation that has passed through a medium that absorbed radiation of certain wavelengths
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Taotao He
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He + Absence = Homo/Dual-sexuality
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Doppler Effect
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change in the apparent frequency of a wave as observer and source move toward or away from each other
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Red-Shift
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occurs when a light source is moving quickly away from an observer
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Blue-Shift
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occurs when a light source is moving quickly toward and observer
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H-R Diagram
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about 90% of stars lie on the main squence. It plots intrinsic brightness and temperature
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Main Sequence
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a diagonal area on an H-R diagram that includes more than 90 percent of all stars
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Red Giant
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a very large red star with little energy produced (eg. Felix Tang)
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Red Supergiant
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a very large star of high luminosity (eg. Benjamin Tang)
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White Dwarfs
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remnants of burn out stars. very hot and small. difficult to find b/c they are so faint (eg. Harmony Hsia)
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Black Hole
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a region of space resulting from the collapse of a star (eg. D-Wang)
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Eclipsing Binary Stars
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a star system in which one star periodically blocks the light from another
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Spectroscopic Binary Stars
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Two stars whose presence that can be decuded by the stellar spectra.
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Exploding Star
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Star that ends its life through a cataclysmic outward explosion (eg. Ammar Nasir)
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Parallax Method
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A triangle that is created by Earth, Sun, and a star.
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Absolute Magnitude
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The actual brightness of a star
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Apparent Magnitude
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the brightness of a star when viewed from Earth
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Spectroscopic Parallax
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a methos of determining a star's distance from the Earth by measuring its surface temperature, luminosiry, and apparent magnitude
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Cepheid Variable
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A star of variable luminosity. The luminosity increases sharply and falls off gently with a well-defined period. The period is related to the absolute luminosity of the star and so can be used to estimate the distance to the star.
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Olber's Paradox
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If the universe has infinite time and space, there would be an infinite number of stationary stars, making the night sky bright, which is not the case.
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Big Bang Theory
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(cosmology) the theory that the universe originated 13.7 billion years ago from the cataclysmic explosion of a small mass of matter at extremely high density and temperature
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Constellations
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a group of stars that forms a shape or pattern
