Astronomy Essay Questions

Question 1)                             80 Points                                 ~ 200 Words What are the differences between the Apparent Magnitude m, and Absolute Magnitude M ?  The brightness of an object depends on its distance in what way,  i.e. what is the term for this mathematical relationship?  From what distances are m & M determined?  Compare M  to the Luminosity L, which does not depend on distance. How are they similar?  If you take the difference of the Apparent Magnitude and Absolute Magnitude, i.e.  m – M = X,  what important quantity can you determine?   What is a “Standard Candle”?   Question 2)                             40 Points                                 ~ 100 Words Discuss the Hertzsprung–Russell diagram.  What types of variables are plotted on the horizontal and the vertical axes of the diagram?   What are the four main regions of the diagram,  and what kinds of stars are found there?  Why is the H-R diagram so useful in Astronomy?   Question 3)                             80 Points                                 ~ 200 Words For a star to be on the Main Sequence of a Hertzsprung–Russell diagram, what nuclear fuel must it be “burning” in its core?  Main Sequence stars must also be stable. This is known as Hydrostatic Equilibrium.  What are the two forces involved in Hydrostatic Equilibrium?  How does the Mass of a MS star effect its temperature, and hence its lifespan on the Main Sequence?  Compare the Main Sequence lifespans of a red dwarf star, a yellow star like our Sun and a blue giant star.  What happens to a star when it leaves the Main Sequence?  What are the two end results for a star when it exhausts its nuclear fuel,  and how does it depend on the star’s Mass?