Physics 110: Homework Questions

(Handout #3)

Homework #5 Due 25 Feb Deadline 1 Mar

5.1

Describe the changes in the Sun that will occur as a result of the Sun's main sequence evolution. What effects will these changes have on the Earth?

5.2

What are the minimum and maximum masses of stars on the main sequence? What sets these limits?

5.3

If a cluster is observed to have O stars in it, how do we know that it must be a young cluster? Is it possible for the same cluster to also contain M stars? Explain.

5.4

What are Cepheid variable stars and why are they important to astronomy? Describe the relationship between pressure and gravity throughout a pulsation cycle of a Cepheid variable.

5.5

Why is it not possible for stars to create the elements heavier than iron by fusing lighter elements? How were the chemical elements heavier than iron created?

Homework #6 Due 4 Mar Deadline 8 Mar

6.1

Contrast the equation of state of a normal gas with that of a degenerate gas. List three situations where the degenerate gas equation of state plays an important role in our theories of stellar evolution.

6.2

A 2 core of a star contracts after using its nuclear fuels. Explain why we can be sure that the star will not become a white dwarf. What is the minimum main sequence mass of this star?

6.3

What is the observational difference between type I and type II supernovae? This difference is an extremely important clue into the nature of the two types of supernovae. Explain why.

6.4

Why would no pulses be observed from a rotating neutron star if its magnetic axis and spin axis were aligned? Why don't we see any pulsars with periods longer than a few seconds? What is the minimum possible period of a pulsar and why?

6.5

Describe what we would see if we watched an object fall toward a black hole. What would happen to the distance of the Earth from the Sun and the length of the year if the Sun were instantly replaced by a 1 black hole?

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