WK6HW - JO

# WK6HW - JO - 1 Calculate the distance of the following...

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1) Calculate the distance of the following stars: a) Star A has a parallax of 0.2 arc seconds d = 1/p d = 1/0.2 d = 5 5 pc b) Star B has a parallax of 0.04 arc seconds d = 1/p d = 1/0.04 d = 25 25 pc c) Star C has brightness difference in apparent and absolute magnitude (m-M) of 5 magnitudes. d = 10^(m-M +5)/5 d = 10^2 d = 100 100 parsecs 2) How can a cool star be more luminous than a hot star? Give an example. The hot main-sequence stars are more luminous then the cool main-sequence. There are however, stars that don’t fall on the main-sequence. This shows you that temperature is not the only thing that determines the luminosity of a star. Size is also important. An example of this would be stars called giant. They lie at the right

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above the main sequence. Although these stars are cool, they are luminous because they are 10 to 100 times larger than the sun. The super giants are even more luminous and lie near the top of the H-R diagram; they are 10 to 1000 times the radius of the sun. 3) What are roughly the radius size and absolute magnitude of the following stars? (Hint: use the H-R diagram on page 184) a) G2 V Absolute magnitude: + 5 Radius size: 1 b) G2 III Absolute magnitude: 0 Radius size: 10 c) G2 Ia Absolute magnitude: - 5 Radius size: 100 4) What are the types of nebulae? Describe them in detail. Emission nebulae – are produced when a hot star excites the gas near it to produce
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WK6HW - JO - 1 Calculate the distance of the following...

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