SPECIAL NOTE:  See the following page for an attempt to clarify the text discussion of nuclear reactions and the connection with stellar evolution.  In addition, there is an informative online description of energy production in all kinds of stars at the following website:  http://nrumiano.free.fr/Estars/energy.html

1.  Read the units in the textbook, list questions you have about the reading, and ask them during class time.

1a.  For an introduction to this week's topics, see my week 4 instructor notes.

1b.  To read about the long history of discovering brown dwarfs (sub-stellar objects), see the Scientific American article, "The Discovery of Brown Dwarfs," by Gibor Basri:  April 2000, page 76.  The article will help understand "what if" gravitational collapse does not generate high enough temperature in an object to cause hydrogen (protons) to fuse to produce helium (i.e., what stops the gravitational collapse before the temperature gets to 6 million Kelvin?).  For a quick summary of formation of brown dwarfs, see the following page for information I present in class:  BROWN DWARF FORMATION

1c.  For some HST visible light and infrared images (using NICMOS camera) of dusty disks (a predicted early stage of star formation), see the following link: 
http://hubblesite.org/newscenter/archive/1999/05/image
In particular, compare the infrared and visible images for the two forming stars DG Tau B and Haro 6-5B.  The visible images show jet activity, and the infrared images clearly show the inner part of the disk in each system.  Finally, note the set of links on the left side of each of the two pages.   Try the "videos" link, and in particular check out the quick-time movie, which loads relatively quickly, to see an animation of star formation, including the disk phase.

1d.  For a variety of educational images, at various wavelengths, of star formation, see the following page:
Star Formation Images

2.  Respond with written answers to the Week 4 discussion questions.   I'll take questions about these during class time.   Assess your responses by comparing with my Week 4 DQ responses on this web-site, as instructed on my responses page.  Turn these in the first day of unit 5.