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10 Cards in this Set
- Front
- Back
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Trigonometric parallax
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method used to determine distance of near by stars
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1 parsec (ps) =
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1" or 3.26 ly
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Ground based astronomers cannot measure a parallax smaller than...
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.02", or 50 pc
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Radial velocity
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measured along the line of sight by the doppler shift.
Blue shift = moving toward earth Red shift = moving away from earth |
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Transverse velocity
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measured perpendicular to line of sight.
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To measure the transverse velocity....is used?
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Proper motion- angular movement of star across the sky asfE
& the distance to the star. |
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Real motion is a combination of what?
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Radial motion and transverse motion asfE
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Apparent brightness
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observed property of the star dependent on it's distance from earth, measure using the magnitude scale
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Luminosity = absolute brightness
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intrinsic property of the star, distance doesn't matter, and is expressed in absolute magnitude.
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Flux & inverse square law
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Flux - apparent brightness (energy flux) varies as luminosity/distance^2
Square law -The farther the source from the observer the fainter (diluted) it becomes. |
