AST 307 · Introductory Astronomy Fall 2003 Topics Chapter 19  Oct. 22 What forces tend to pull a molecular cloud together, and what forces tend to resist its contraction? Describe the concept of equilibrium. What does it mean to say that a protostar is in hydrostatic (or pressure-gravity) equilibrium, but not in thermal equilibrium? What happens as a result? How can we observe protostars, and how do they differ in appearance from main-sequence stars?

29 October 2003 Astronomy Program · The University of Texas at Austin · Austin, Texas 78712 prospective student inquiries: studentinfo@astro.as.utexas.edu site comments: www@www.as.utexas.edu