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### 10 Cards in this Set

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 What's the difference between apparent brightness and luminosity? Apparent brightness is how a star appears to the naked eye and varies with distance. Luminosity is the true brightness of a star and does not vary. How does apparent brightness change with distance? Apparent brightness changes with distance squared. What are the ranges of stellar luminosities of L(sun)? Lowest = 10^(-4) Highest = 10^(6) What is stellar parallex? Small annual shifts to a star's apparent position caused by Earth's motion around the Sun. What is a parsec and an arcsecond? An arcsecond is 1/3600 of a degree. A parsec is the distance to an object with an angle of 1 arcsecond, which is about 3.26 light-years. How does the parallex of a star change with distance? Closer stars appear to have more parallex while distant stars appear to have none or very little parallex. This is because closer objects have a larger parallex angle and distant objects have a smaller parallex angle. How does the luminosity of a star vary with temperature and radius? The hotter a star is the more luminous it is because it emits more energy per meter square. The bigger a star's radius is the more luminous it is because the more "meter's square" it has the more collective light it can give out. What is a spectral type? A way to classify stars based on temperature. What are the ranges for each of the different spectral types? O >30,000K B 30,000 - 10,000K A 10,000 - 7500K F 7500 - 6000K G 6000 - 5000K K 5000 - 3500K M < 3500K What are the most obvious and common spectral lines in A, G and M type stars? A - lost of strong hydrogen lines G - weak hydrogen lines, strong ionized calcium lines M - Strong molecular lines