Preflight 1

Post your response on the course Compass site

Due Friday, Sept. 4, 12noon

Suggested Readings:

Asplund, Grevesse, and Sauval 2005, ASP Conference Series 336, 25 (electronic version also available here)

This important paper argues for a substantial revision in our understanding of solar system heavy element content.

Boyd: Chapter 1.2 (nuclear abundances); Chapter 3.1-3.5 (nuclear physics)

The discussion of abundances is brief and summarizes many of the same points made in class. The nuclear physics discussion is quite extensive and provides an excellent introduction.

Questions

The questions are really meant to help guide your thinking as you read. You may find it helpful to look at the questions first and bear them in mind as you read.

1. We'd like to know a little bit about you for our files. Briefly, what is your background in astrophysics? In nuclear/particle physics? If you are already involved in research, what are you working on? If you are not, what area(s) interest you?

   What topics would you most like see discussed in this course?

2. Solar System Abundances I: The Good

   1. The "solar system abundances" we keep referring to in class are called by many names in the literature. These abundances are also sometimes referred to as "cosmic abundances," or "solar abundances," or "standard abundances." Which name is the most precise? Which is the least precise? What assumptions are implied by each name? If you are unsatisfied by these terms, suggest an alternate term which is short enough to use but in your view most accurately characterizes the nature of these data.
   2. What measurements lead to these abundances? How are these measurements linked to put all of isotopes on the same plot?
   3. How do we know that nuclear physics has led to the observed abundance pattern?
   4. What nuclear property leads to the "zig-zag" nature of the curve as it goes from one point to the next? What is the underlying physics of this nuclear property?

3. Solar System Abundances II: The Bad and the Ugly (optional). For many years solar system abundances became ever more precisely known, but without major changes. However, Asplund, Grevesse, and Sauval (2005) argued for substantial changes in some key element abundances compared to older results (incluing the Anders & Grevesse values shown in class and on your handy abundance table). These changes have important consequences.

   1. Please skim the article in order to find the main arguments and results. What have the authors (you can call them AGS for short) done differently than previous work? Why do they believe their analysis is better?
   2. What abundances change the most due to their analysis?
   3. What consequence do these changes have?
   4. This paper has been cited 700 times, and has been refereed to by papers in many areas of astronomy, cosmology, and astrophysics. Why has its influence be so broad?
4. Compare the nuclear and electromagnetic interactions. In what ways are they similar? Different? Be as complete as possible within 1pgh.
5. What is the nuclear shell model? How does the nuclear shell behavior compare to that of electrons in atoms? Give three examples of nuclei which are particularly stable due to shell effects, and use the shell model to explain the absence of stable nuclei at mass A=5 and A=8.
6. What material did you find difficult, confusing, or unclear? What material would you like to know more about?
7. Other questions or comments?