1) Star A has a temperature of 12,000 K, about twice that of star B, the spectrum of which is shown below for reference.

a) (8 pts) On the same graph below, sketch the spectrum of star A. Pay careful attention to the location of the peak wavelength and the intensity across the spectrum!

b) (6 pts) Next to the graph, state which star emits more red light. In other words, if we viewed star A and star B side-by-side through a filter that only allowed red light through, which would appear brighter? Briefly explain your answer.

2) We know that the Sun's energy comes from nuclear fusion, a process we are trying to replicate for our own uses here on Earth.

a) (8 pts) Once energy is generated in the core of the Sun, it travels outward through the envelope. Explain why energy travels differently in the radiative and the convective zone.

b) (6 pts) Explain how inertial and magnetically confined fusion reactions work.

3) Though Astronomers have searched extensively for signals from alien civilizations, so far, we've had no luck. Some scientists like Peter Ward feel that we are very unlikely to ever contact a civilization like our own because the development of technology, even among planets which had advanced life forms, will be too unlikely.

a) (6 pts) Explain why Ward thinks that even among sohpisticated species, technological development (thus, radio telescopes) will be extremely unlikely in the Universe.

b) (8 pts) Some believe in the existence of extraterrestrial life so strongly that it is virtually indistinguishable from an irrefutable belief! Briefly describe the major benefit and the major drawback to systems of thought based on irrefutable beliefs.

4) Issues of science and philosophy were brought up in Feynman's "Cargo Cult Science" lecture and in our study of the solar neutrino problem.

a) (6 pts) Feynman brought up the example of Mr. Young, who developed rat-running experiments. What was it about Young's experimental methods that made them such a great example of the scientific method compared to other experiments?

b) (8 pts) Briefly explain what the solar neutrino problem was and explain one reason why scientists did not abandon the nuclear fusion model for the Sun as a result of it.

5) The constellation Leo is prominent in the evening sky at 10pm tonight.

a) (8 pts) Draw a simple star chart, name a bright star in Leo and give an approximate location (altitude and azimuth) for this constellation at 10pm tonight.

b) (6 pts) Assume the bright star in Leo is identical to our own Sun in terms of its spectrum (peak wavelength, spectral lines, etc). If this star is too far away from our parallax technique to work, how could you find the distance to it?

6) Atmospheric effects on starlight are often a real problem for Astronomers, but we have some ways to compensate for them.

a) (8 pts) Explain what causes "seeing" (which makes stars tend to twinkle). As part of your answer, explain why planets don't twinkle.

b) (6 pts) Explain how adaptive optics works to correct for atmospheric seeing.

7) Temperatures in the Sun's corona often reach millions of degrees, much hotter than the photosphere. One way we can measure the temperature of gas in the corona is by looking at spectral emission line widths.

a) (4 pts) Some of the first Astronomers to survey the corona found patterns of unfamiliar spectral lines that they dubbed "coronium". Name one of the elements that makes up coronium.

b) (10 pts) Explain why broader lines are associated with higher temperatures.

8) To determine the mass of the central star in a binary system, we use Doppler shift information and some basic math. For example, suppose we see an edge-on binary system in which the spectral lines are going through a merge-split-merge-split pattern.

Describe how we could determine the mass of the central star in this system. What measurements must we make, and how do we use these measured quantities to find mass?