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What is the relation between a star's apparent magnitude and absolute magnitude?
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M - M = 5 log(d/10)
or m - M = 5 log(d) - 5 Where m = apparent magnitude M = Absolute magnitude d = distance to star in parsecs |
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What is the order of spectral classes in order of decreasing temperature?
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OBAFGKM
("Oh, be a fine girl, kiss me") |
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A star with surface temperature of 5800 K and a luminosity of greater than 100 times that of the sun is a member of which luminosity class?
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III Giant
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A star with surface temperature of 5800 K and a luminosity of greater than 1000 times that of the sun is a member of which luminosity class?
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I Supergiant
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A star with surface temperature between about 6000-20000 K and a luminosity less than 100 times that of the sun is a....
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White dwarf
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What is the relation between distance and parallax?
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D = 1 / p''
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A magnitude difference of 1 corresponds to a factor of ____ in brightness
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2.512
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The color index of a star (the difference between the apparent magnitudes B and V at two different colors, blue and visual) is a direct measure of what property of the star?
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Surface temperature
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Compared to a star in the middle of the HR diagram, a star in the lower left part is...
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Smaller
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Compared to a star in the middle of the HR diagram, a star in the upper right part is...
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Bigger
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Giants and supergiants make up about what percentage of stars in the sky?
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About 1%
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About how big are white dwarfs?
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Approximately the same size as Earth
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What proportion of visible stars in the nighttime sky are binary or multiple-star systems?
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Nearly 50%
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What is Kepler's third law?
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M1 + M2 = a^3 / P^2
Where M1, M2 are masses of two stars in a binary system, in solar masses a = semimajor axis of one star's orbit around the other, in AU P = Orbital period, in years |
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What is the density of a white dwarf?
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P = 1.6 x 10^5 g/cm^3
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