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8 Cards in this Set
- Front
- Back
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stellar radii
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luminosity=area x intensity
L=r^2 T^4 stars with radii greater than 10 s.radii= giant stars stars with radii less than 10 s.radii= dwarf stars sun is 1 solar radii |
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selection effects
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most common stars are high luminosity O and B main-sequence, as well as giants and supergiants
most common are very faint stars: lower main-sequence red dwarfs; white dwarfs |
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spectral line broadening
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smaller stars have denser atmospheres
luminosity class bigger the star, the thinner the spectral line/the more the gases are spread out |
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binary pairs
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2 stars which revolve around common center of mass
the heavier mass is closer to the center of mass Ma+Mb=a^3/ P^2 |
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spectroscopic binary systems
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orbital pd (P):how long it takes to go thru one complete cycle
orbital velocities (v):doppler shifts->radial velocity of each star radii of orbits(a):pd times velocity gives circumfrence of orbit doppler shifts only measure radial motion |
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eclipsing binary systems
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when small star crosses in front of large, we decrease in brightness
when small star is eclipsed behind star, brightness drops |
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mass-luminosity relation
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hotter stars are more massive than coller stars
L=M^3.5 a star twice as massive is MORE than twice as luminous |
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main-sequence lifetimes
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stars spend 90% of lives on the main-sequence
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