Homework 9 Unsolved Questions - Astronomy | AST 192, Assignments of Astronomy

Download Homework 9 Unsolved Questions - Astronomy | AST 192 and more Assignments Astronomy in PDF only on Docsity! Astronomy 192 Section 001 Homework 9 – Due Wednesday, March 23rd Name _____________________________________________ Student Number (Last 4 digits only!) _____________________ The purpose of this assignment is to review some of the topics covered in earlier chapters in light of what you know from Chapters 15-17. Part I. Earth Stuff = Star Stuff. (50 points) Reread “Our Cosmic Origins”, “Expansion versus gravity” and “Star Stuff” from pages 6-8 of your text before answering the following questions. A. Which two elements were most abundant in the early Universe? B. Which two elements are most abundant in the existing molecular clouds in our Milky Way Galaxy? C. Which two elements are most abundant in our Sun? D. Which chemical element is the most common byproduct of helium fusion in low-mass stars? E. White dwarf stars are most likely composed of which element? F. The simplest organic molecules are composed of which two chemical elements? G. Processes in which heavy nuclei are formed from lighter ones are called? H. Processes in which heavy nuclei break into smaller fragments are called? I. Which of the two processes described in G and H is currently used in nuclear reactors on Earth? J. Which nucleus is stable against either of the processes in G and H? Part II. (30 points) Reread “Galactic rotation” on pages 18-19 of your text before answering the following questions. A. Roughly how many orbits of the Milky Way galaxy has our Sun made since it was formed 4.6 billion years ago? B. What is a typical lifetime (in years) of an O-type star? (Hint: take a look at the H-R diagram.) C. Consider an O-type star as in Part B. If that star were orbiting the center of the Milky Way along with our Sun, how many orbits (or what fraction of an orbit) would it make during its hydrogen-burning lifetime?