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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