Final Examination

Due: Thursday, March 16, 1995

Answer 6 out of the following questions

Question 1

Stellar spectra indicate many things about stars. In this question consider the temperature. Use the shape of the continuous spectrum to

estimate the surface temperature of the B5 III star
estimate the surface temperature of the K4 III star

Are these temperatures consistent with the strengths of the hydrogen lines in these stars? That is, do your answers make sense?

Estimate how large the errors contained in your answers are. Be careful to describe explicitly how you arrived at your answers and your error estimates.

Question 2

In the early Universe, element production more or less stopped with helium. Explain why the early Universe is not good at making more massive elements. Why are stars better?
How are elements like uranium (i.e., the elements with more protons than iron) formed? Does this process occur in the Sun? Explain why it does or why it does not.

Question 3

Trace the line of logic which tells you why the mass of a star determines its structure given the constraints laid out in the Russell-Vogt Theorem.

Question 4

What is a neutrino?
What are the various Solar Neutrino Experiments? What are the results of these experiments?
Solar neutrinos (and, in fact, any neutrino is exceedingly difficult to detect), so why do we go to all of the trouble to study solar neutrinos (rather than to simply study the photons from the Sun)?

Question 5

What is the solar neutrino problem? Does this problem invalidate all of our work on stars, that is, does this problem mean that we do not understand stars at all? Explain why or why not.
What are the possible resolutions for the solar neutrino problem?
How can the ambiguities be resolved?

Question 6

Estimate the ages of the following stellar clusters.

Be sure to explain what you did and also estimate the error in your guess. Assume that everything that I have told you in the course is true so that the error is simply determined by how well you measured things.

Question 7

Explain why the report of cold fusion in the late 1980's was most likely nonesense. [Hint--why does fusion only occur near the core of the Sun?]

Question 8

Main sequence (MS) stars do not have arbitrary masses.

MS stars are more massive than ~ 0.1 M(Sun) (FYI, see the HST press release)
MS stars are less massive than ~ 50 - 100 M(Sun)

Explain why the masses of Main Sequence stars are constrained to this rather narrow range of values.

How would these limits change (if at all) if stars were pure helium?