Fall 2009 ASTR 2030 Homepage

This Final review sheet is posted at http://casa.colorado.edu/~ajsh/astr2030_09/review_final.html

The Special Relativity midterm review sheet is posted at http://casa.colorado.edu/~ajsh/astr2030_09/review_sr.html
and the General Relativity midterm review sheet at http://casa.colorado.edu/~ajsh/astr2030_09/review_gr.html

Fall 2009 ASTR 2030 Final Review

The final will be at 1:30-4pm on Saturday Dec 12, in our usual classroom Duane G1B30.

The final will test everything cumulatively over the semester. Check out the weekly summaries, and the clicker questions.

The format will be similar to that of the midterms, only longer. The questions will be mostly multiple choice, graded by scantron (which speeds grading), but there will also be a few short answer questions.

Review Questions

1. How to Script a Movie. Describe the 3 parts of a well-structured movie script.

2. Escape Velocity. During this course we have come across several examples where we have been able to deduce things from the equation v = (2 G M / r)1/2. What do the symbols in this equation signify? Give several examples of where we have applied this equation. In each case, was the equation applied exactly, or just as an order of magnitude estimate?

3. Cold Matter. Why is a liquid or solid almost "incompressible"? At high enough pressure, a liquid or solid can be compressed; what is the condition for this to occur? What happens then? Give an account of what happens to a sphere of cold matter as you increase its mass. Follow the stages through planet, white dwarf, neutron star, black hole.

4. White Dwarfs. What is a white dwarf? What kind of pressure supports a white dwarf? Give an account of this pressure. Can particles at zero temperature move? Can matter at zero temperature have a nonzero pressure?

5. Chandrasekhar Limit. What is the Chandrasekhar Limit? What causes it? What happens if a white dwarf exceeds the Chandrasekhar limit?

6. Neutron Stars. What is a neutron star? What kind of pressure supports a neutron star? Why are neutrons able to withstand a higher pressure than electrons?

7. Core Collapse Supernovae. What is a core-collapse supernova? Give an account of the evolution of a massive star just before core collapse. What is the core made of just before core collapse? Why? What has the Chandrasekhar limit got to do with core collapse? How does the core convert into being made of neutrons?

8. Pulsar. What is a pulsar? The Crab nebula is thought to be the remnant of the Supernova of 1054. How does the Crab nebula support Zwicky's idea that supernovae result from the collapse of the core of a massive star to a neutron star?

9. X-Ray Binaries. If you could see in x-rays, the brightest objects in the x-ray sky would be x-ray binaries in the Milky Way. What is an x-ray binary? How does the evolution of two stars in a binary system lead to an x-ray binary? Where in the x-ray binary are the x-rays produced? Why x-rays rather than, say, visible light?

10. Accretion Disks. What is an accretion disk? What is the observational evidence for accretion disks? Why does material tend to form into an accretion disk rather than falling directly on to a neutron star or black hole? What is the source of energy that heats an accretion disk?

11. Active Galactic Nuclei. What is an Active Galactic Nucleus (AGN)? Name several phenomena associated with an AGN.

12. Jets. What is the observational evidence for jets? In what kind of electromagnetic radiation are jets commonly observed? The radiation is mostly synchrotron radiation. What is synchrotron radiation? Two pieces of observations that at at least some jets are moving at very close to the speed of light are (1) superluminal motion, and (2) one-sidedness. Explain what each of these is, and why they are considered to be evidence for relativistic motion.

13. MAXIM. MAXIM (MicroArcsecond X-Ray Imaging Mission) is a proposed NASA mission which may fly in several decades. What kind of telescope is MAXIM? What is the purpose of MAXIM?

14. Black Holes and the 2nd Law of Thermodynamics. The 2nd law of thermodynamics asserts that “entropy always increases” in time. What is entropy? Black holes seem to violate the second law, because they appear to destroy entropy when they swallow matter. How did Hawking's work resolve the problem? According to Hawking, what is the entropy of a black hole?

15. Hawking Radiation. What is Hawking radiation? Give a rough explanation of how it is produced. What kind of spectrum does it have? The most important thing to know about Hawking radiation is that the characteristic wavelength is roughly equal to the Schwarzschild radius. What does this imply about the Hawking temperature of Hawking radiation? What would a black hole look like if detected in Hawking radiation? Is Hawking radiation from real astronomical black holes observed or observable? Classically, an object that falls into a black hole appears to an outside observer to become extremely redshifted and frozen at the horizon. How does the presence of Hawking radiation modify this picture?

16. Black Hole Evaporation. Black holes lose mass by Hawking radiation, and can eventually evaporate. For what kind of black hole is evaporation important? Do such black holes exist? Could such black holes exist? Roughly how much energy does an evaporating black hole produce when it explodes?

17. Gravitational Waves. What is a gravitational wave? What kind of system produces gravitational waves? Have astronomers seen gravitational waves? Are astronomers likely to see gravitational waves at some time in the future?

Updated 2009 Dec 7