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Chapter 8-9

# Chapter 8-9 - Astronomy odd numbered-Homework Chapter 8 1...

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Astronomy –odd- numbered -Homework Chapter 8 1. if a star has a parallax of .050 second of arc : ð = 20 * 3.26 ly = 65.2 ly ð = 65.2 * 63,241.1 = 4,123,320 AU 3. if a star has a parallax of .016 second of arc, and an apparent magnitude of 6 ð distance = 1/ .016 = 62.5 parsecs = (62.5 * 3.26) ly = 203.75 ly - with this answer, the absolute magnitude is 2 5. d1 = .5 km = 500 m, The absolute magnitude of an object at a distance of 10 pc = 3.086e17 m. d2 = 3.086 e17 m F = (d2/d1 )^2 = [( 3.086 e17)/(500)]^2 = 3.81 e29 we have M1 = 6 According to this formula, the absolute magnitude of a firefly M2 is M2 = M1 + 2.5 * log (F) = 6 + 2.5 * log (3.81e29) ~ 80 7. we know that, the temperature of the sun T_sun is 5,780 k à Half of that T_half is 2,890 K if the star is ten times the radius of the sun and half as hot, the luminosity is : = radius^2 (T_half / T_sun) ^4 = 10^2(2,890/5780)^4 = 6.25 Solar luminosity's So, the star will be 6.25 times more luminous than the sun. 9.

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Chapter 8-9 - Astronomy odd numbered-Homework Chapter 8 1...

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