Preflight 5

Reading:

Stan Woosley & Thomas Janka, "The Physics of Core-Collapse Supernovae" (2005): Nature Physics 1, 147 or astro-ph/0601261

A brief and accessilbe discussion of supernova physics. You can (for now) skip the part on gamma-ray bursts and the r-process.

Recommended:

John Bahcall, "Solar Models and Solar Neutrinos" (2005): Physica Scripta, T121, 46-50 or hep-ph/0412068

One of John Bahcall's last papers, a very readable discussion of his standard solar model, and it's role in the solution of the solar neutrino problem.

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. Solar Neutrinos.
   1. How are solar neutrinos detected? What is the stongest evidence that these neutrinos come from the sun? What in turn does this tell us about the sun?
   2. In his paper, John Bahcall recalls that

      For most of the period of 1968-2001, [...] the great majority of physicists believed that solar neutrino experiments indicated the need for improvements in the solar model, not in the standard model of particle physics.

      To appreciate one reason why this might have been the case, consider the data available at the time. Which of the solar neutrino sources (pp, ⁷Be, and ⁸B) are the easiest to measure? How sensitive are these to the solar central temperature? What does this mean for solar model builders who hope to predict the sun's neutrino output?
   3. How did the SNO experiment so dramatically establish that new neutrino physics is indeed the explanation of the solar neutrino problem? Why don't the SNO conclusions depend on the details of solar models?

2. Core-Collapse Supernovae.
   Read the article by Woosley & Janka; you may skip the sections on gamma-ray bursts and the r-process.
   1. Supernovae are classified into two basic varieties: Type Ia, and the others which are mostly Type II (but also Type Ib, Ic). What is the observational basis for these categories? What physically is different about these two kinds of explosions?
   2. What is a "core collapse," and what stars suffer this fate? In what form is most of the energy released in a core-collapse explosion, and how do we measure this? Roughly what fraction of the total energy is represented by the optical outbursts?
   3. Theoretical studies of core-collapse supernovae have the notorious problem that it is very difficult to make the models explode. What occurs in the models which fail to explode? What extra physics--not yet properly in the modles--might "cure" this problem?

3. What material did you find difficult, confusing, or unclear? What material would you like to know more about?

4. Other questions or comments?