1) A black hole has a mass that is 10,000 times the mass of the Sun. What is its Schwarzschild radius? Show all work for full credit.

2) A Cepheid Variable star has a period of 10 days. What is its luminosity?

3) A main sequence star has a mass of 8 solar masses and a luminosity of 1,000 solar luminosities. What is its main sequence lifetime? Show all work for full credit.

4) Why aren't Type II (core collapse) supernovae used as standard candles while Type Ia supernovae are used as standard candles?

5) Carl Sagan once said "We are Star-Stuff". What did he mean?

6) A number of particles are produced during the fusion reaction in the Sun. What particles are produced and what happens to the particles after they are created (their final fate)?

7) Put these main sequence stars (A2, B4, F6, G9, O8, M5) in order of increasing surface temperature, increasing mass, and increasing main sequence lifetime.

Low → High Temperature

Low → High Mass

Short → Long Main Sequence Lifetime

8) What is the main deciding factor whether a main sequence star becomes a white dwarf, neutron star, or black hole? Why?

9) How can you use the Hydrogen 21-cm line transition to measure the rotation curve of a galaxy?

10) Why are Cepheid Variables used as standard candles?

11) How would you estimate the number of stars in a galaxy?

12) Why do we think most of the mass of our galaxy is made of dark matter?

13) If 10% of the mass of the Sun is hot enough to undergo fusion into Helium during its lifetime, how much energy will be produced?

14) Why doesn't fusion occur on the surface of the Sun?

15) Show how you would estimatehow many planets exist in the universe. Explain all parts of your calculation. Give your estimate.

16) What are two pieces of evidence that the Big Bang occurred?

17) Why won't our Sun become a Type Ia supernova?

18) What is evidence that galaxies merge together?
 
19) Why do we think life could have existed on Mars?

20) Why do we think pulsars are rotating neutron stars?

21) A galaxy has a recession velocity of 100,000 km/s and follows Hubble's Law. How far away is the galaxy from Earth? Show all work for full credit.

22) How is Hubble's Constant calculated?

23) Using the Drake Equation, estimate the number of communicating civilizations in the galaxy. Explain what all the variables mean and the values you use. Pick realistic values.

24) Give 10 solutions to the Fermi Paradox.

25) How much energy is released when a positron and aan electron collide? Show all work for full credit.