Review Sheet: Test 3
Date of Exam: August 25, 2009

Version Date: August 23, 2009

Lifetime of a Main Sequence Star with mass M > 0.7 Solar Masses:
lifetime = [M/(Mass of Sun)]^-310¹⁰ years

Old Test
Topics:
STELLAR PROPERTIES

What are Main Sequence Stars, giants (Red Giants), Super-Giants, Asymptotic Giant Branch (AGB) stars, white dwarfs, planetary nebulas, neutron stars?
What is the Mass-Luminosity relation? How can it be used to infer a scaling law for stellar lifetimes? What stars have the longest lifetimes, massive orlow mass stars? What is the argument one uses to infer the relationship which describes how the lifetime of a star depends on its mass?
What is the luminosity function? Which type of stars are the most numerous in our Galaxy?

Poperties of the Sun:

What is the Solar Activity Cycle? What features of the Sun vary over the course of the Solar Activity Cycle?
What is meant by the Quiet Sun? What is meant by the active Sun?
Describe the appearance of the Quiet Sun and list its properties. What are the properties of the photosphere, the chromosphere, the corona? Why is the Corona hotter than the Photosphere? What is the transition region? What is granulation? What causes granulation?
What are sunspots? What are the umbra and the penumbra of a sunspot? How many times brighter is the surrounding Solar photosphere than the umbra of a sunspot? What are plages? How long do sunspots live, on average? What about sunspot groups?
What are quiescent and eruptive prominences? What is the Solar Wind? What are coronal holes? What are filaments? What are flares? How are flares classified? What are CMEs? What effects do flares and CMEs have on the Earth? What property of the Sun seems to unite all the phenomena of the Solar Activity Cycle? roughly, describe the mechanism which is though to drive the Solar Activity Cycle. The Sun is in differential rotation. What does this mean?
What is the period of the solar activity cycle? Is this the same as the period for the variation of the number of sunspots visible on the surface of the Sun? What is the Butterfly Diagram? What is the Maunder minimum? What is the significance of the Little Ice Age which struck Europe in the mid 1600s (in terms of Solar variability)? Roughly, how large is the variation of the Solar power (Solar constant) over a Sunspot cycle. Are there noticeable effects of this variation on the climate of the Earth?

What are the different ways discussed in class that the Sun and stars can generate energy? What is the most efficient way to generate energy of those mentioned in class? What mechanism is used by Main Sequence stars to generate energy? Is energy strictly conserved in the Universe? What physical concept underlies the famous Einstein result that E = mc²? What is annihilation?
Nuclear Energy Generation--the conversion of 4 hydrogen nuclei into a helium nucleus + energy + other particles. What are neutrinos? Why is nuclear fusion so difficult (that is, what is the major impediment to fusion)? li>What is the proton-proton cycle (pp-cycle)? What is the carbon-nitrogen-oxygen cycle (CNO cycle)?
How can fission and fusion both generate energy? In this context, why is iron such an important elemnet? Since fusion and fission can both generate energy, does it then follow that nuclear reactions are a source of unlimited energy?
What are the energy transport mechanisms used by stars? Which ones are the most important for the Sun?
What important role outside of energy transport does convection play in the observable properties of the Sun?
Why is qunatum mechanical tunneling important for stars? What is the Heisenberg Uncertainty Principle? Compare and contrast matter and anti-matter. What is annihilation? What is the matter/anti-matter asymmetry problem?
What are Solar oscillations? What role do Solar oscillations play in our understanding of the interior of the Sun?
Main Seqeunce stars are in equilibrium; both mechanical equilibrium (hydrostatic equilibrium -- stars are not changing in size very quickly) and thermal equilibrium (the temperature structures of stars are not changing very quickly -- the energy losses due to radiation and particles from stars are roughly balanced by the energy production due to nuclear fusion reactions).

Hydrostatic Equilibrium -- We need to address what holds stars together (gravity), and to address what keeps stars from collapsing into dense balls (gas pressure).
Thermal Equilibrium --We need to address the energy source for stars and how stars lose energy.
Why are neutrinos so much useful as probes of the interior of the Sun than are photons (the light we receive from the Sun)? What other methods are used to probe the interior of the Sun? What was the Solar Neutrino Problem? How was the Solar Neutrino Problem resolved?

STAR FORMATION

Is star formation an ongoing process in our Galaxy? How do we deduce whether or not star formation is an ongoing process? Will the star formation process continue forever?
How do we estimate the lifetimes for Main Sequence stars? What is the rough scaling relation for the lifetimes of Main Sequence stars as a function of the stellar mass (for stars more massive than about 70 % of the Sun's mass)? How did we derive this relationship? Estimate the lifetimes for stars of various masses.