1	Homework #8 Question 1 (1 point) Sunsets appear red for the same reason that some stars in space appear red -- they are both seen through dust particles. Why does this make them appear red? a.The dust is heated and emits red light. b.The dust scatters blue light more than red light, such that more of the red light passes directly though the dust. c.Dust polarizes light which always makes it redder. Question 2 (1 point) The Pleadies is an open star cluster not too far from us. It also represents a textbook example of a type of nebula. Which type is it? a.An emission nebula b.A dark nebula c.A reflection nebula d.A stellar nebula e.None of the above Question 3 (1 point) Stars are born in regions which (before the new stars can modify them) are a.dense cold molecular clouds. b.hot ionized hydrogen regions. c.low density regions between clouds
2	Homework #8 Question 4 (1 point) What do we see in the Orion nebula that indicates it is a region of new star formation? a.Hot O stars b.Herbig-Haro Objects c.Dust Disks around stars d.All of the Above e.None of the Above Question 5 (1 point) The lifetime of high temperature main sequence O and B stars is _____ the lifetime of low temperature K and M stars. (Fill in the blank.) a.shorter than b.longer than c.about the same as
3	Homework #8 Question 6 (2 points) In the movie Blade Runner, replicant Roy Batty was compared to a candle: "A candle that burns twice as bright burns half as long." Star lifetimes are more complex than this (i.e.,the relationship is not linear). If the lifetime of a star is half that of the sun, how luminous is it? a.1 solar luminosity b.2 solar luminosities c.0.5 solar luminosities d.1.3 solar luminosities e.2.6 solar luminosities Need to use L = M^3.5 and Lifetime = M ^-2.5(all in solar units) First, Lifetime = ½ solar = (M) ^-2.5, solve to get M (1.3 solar masses) Plug into the other equation to get 2.6 solar luminosities. It’s really just a matter of being able to solve these exponential equations comfortably with your calculator.