For those of you who did badly on exam 1, you ought to try STARTING
your studying by answering these notes. Write down the answers on a
piece of paper.  If you don't know the answers, find them in your
notes, in the notes we have on the web, on the other readings we have
on the web, in "astro 100" textbooks inthe library...

When you answer these questions, even if we don't explicitly
ask, you should say (and answer) HOW DO WE KNOW THIS and
WHY is this answer plausible and consistent with what we know...

"WHAT" is important, but "HOW" and "WHY" are far more important...


1) How do we use absorption lines in spectra to determine the temperature
of a star (it's NOT the color of the star)?

2) What is the Doppler Effect (Doppler Shift)? How does it work? What
can we learn from it?

3) What determines if the endpoint of a star's evolution is a white dwarf, 
   neutron star, or black hole? What holds the star up against gravity
   in each case? How does stellar mass loss play a role in this endpoint?
   How massive can a white dwarf be? How massive a main sequence star will
   end up as a white dwarf? How massive can a neutron star be? How massive
   can a black hole be?

4) Why is a massive white dwarf actually smaller in radius than a low-mass
   white dwarf (very generally)?

5) Why is a neutron star so much smaller than a white dwarf?
   the sun is about 1.4 million km (anbout 1 million miles) in diameter.
   How big is a white dwarf (in miles and in terms of some object
   whose size we know)? How massive is a white dwarf?
   How big is a neutron star? How massive is a neutron star?

6) Why does binary-star evolution play such an important role in our
   discussion of white dwarfs and neutron stars and black holes?

7) What is a nova observationally? What is our best model of a nova?
   How does this model "make" the energy given off?
   Why are accretion disks a natural consequence of the evolution of close
   binary star systems?

8) Why are ultraviolet telescopes and xray telescopes good equipment to use
   to identify white dwarfs and neutron stars and black holes that
   are members of binary star systems?

9) How do we measure the mass of a black hole or neutron star or white dwarf?


10) Why are neutron stars better places in which to make energetic
    photons than is the sun? (something about the law of gravity)

11) How does "gravitational potential energy" enter into our discussions of
    massive, compact objects?

16) Explain the notion of gravitational radiation. What is the best
observation that hints that gravitational radiation exists?

12) How does a massive star explode?

13) How does a massive star explosion create new elements? 

14) How often does a galaxy like the Milky Way have a massive star explosion?

15) There's a second kind of supernova that comes from a white dwarf in
    a binary star system. How does this work?

16) What is the relationship between neutron-stars/pulsars and supernova
remnants? What is the Crab nebula? When was it created?

17) Explain figure 3.1 in Wheeler.

18) Explain Figure 3.2 in Wheeler.

19) Explain figures 4.1, 4.2, 4.4, 4.5 in Wheeler.

20) Explain Figures 5.1, 5.2 in Wheeler.

21) Explain figures 6.1, 6.4 in Wheeler.

22) Explain figure 8.1 in Wheeler.

23) Explain the first figure in the Oct9 figures on the website.

24) Explain all of the figures in the Oct 21 figures on the website.

25) Why do close binary stars tend to form accretion disks when mass
transfer occurs?

26) Explain how/why an accretion disk can brighten or fade.

27) How do we determine the age of a star cluster from the luminosity
of its main sequence brightest star? (the "main sequence turnoff")

28) Repeat the thought experiment that we did in class that leads to
the answer to the previous question.

29) Naively, supernova remnants look just like planetary nebulae or
star-forming regions. How is it that we know that the supernova remnants
are actually from exploding stars?

30) For what kind of supernova have we actually seen the precursor star?
From what kind of supernova have we actually detected neutrinos on earth?

31) At the top of the Oct23 notes of Jane Rigby, there's a table
of how quickly certain stages of nuclear burning occur in a massive
star. What do we see on the outside of the star before the explosion
actually happens?

32) Explain how core collapse happens in some detail.

33) What happens to the core of a massive-star supernova?
Where does all of the energy in a massive-star supernova come from?

34) Read Jocelyn Bell's recollections of her discovery of Pulsars
(see the figures directory, halloween). 

There will be additional questions soon.