Loading...

ASTR101: Introduction to Astronomy

Unit 11: Stellar Evolution   In this unit, you will be introduced to the way in which stars change over time.  You will learn about the history of our sun and about its future.  You will learn how elements more massive than helium came to be and how they became available to the universe for the production of later generations of stars and their planets.

Unit 11 Time Advisory
This unit should take approximately 14 hours to complete.

☐    Subunit 11.1: 2 hours

☐    Subunit 11.2: 2 hours

☐    Subunit 11.3: 4 hours

☐    Subunit 11.4: 4 hours

☐    Assessment: 2 hours

Unit11 Learning Outcomes
Upon successful completion of this unit, students will be able to: - Identify the conditions that led to the formation of a star from a cloud of interstellar matter. - List the sequence of internal changes that occur in a low mass star, such as our sun, as it evolves from a main-sequence star to a dead star. - Compare and contrast the sequence of internal changes that occur in the evolution of a high-mass star with those that occur in a low-mass star. - List at least three properties that distinguish a white dwarf from a neutron star.

11.1 The Birth of a Star   - Reading: The Saylor Foundation’s “Unit 11: Stellar Evolution” Link: The Saylor Foundation’s “Unit 11: Stellar Evolution” (PDF)

 Instructions: This article provides an overview of the material we
will cover in Unit 11.  Read it carefully, but please don’t think
that you have to fix every single fact into your memory.  What you
should strive for is to be sure that it makes sense to you as you
are reading it and that when you are finished you can briefly
summarize the main points of the reading.  You should read this both
as you start and after you have finished working your way through
the unit.  

 Reading this article should take approximately 45 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Web Media: YouTube: Khan Academy’s “Birth of Stars” Link: YouTube: Khan Academy’s “Birth of Stars” (YouTube)

    Instructions: This video is a blackboard format discussion of the birth of stars.

    Watching this video should take approximately 10 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: YouTube: The Science Channel’s “Stellar Evolution” Link: YouTube: The Science Channel’s “Stellar Evolution” (YouTube)

    Instructions: This video is a somewhat melodramatic, but essentially accurate, overview of stellar evolution focusing on our sun.

    Watching this video should take approximately 10 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Web Media: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “The Interstellar Medium” Link: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “The Interstellar Medium” (HTML)

    Instructions: This article is a thorough discussion of the interstellar medium, the raw material for the birth of stars.

    Reading this article should take approximately 15 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

11.2 Hydrogen Fusion   - Reading: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “The Proton-Proton Chain” Link: The University of Tennessee, Knoxville’s Department of Physics and Astronomy: “The Proton-Proton Chain” (HTML)

 Instructions: This article provides a nice graphic of the
proton-proton cycle of hydrogen fusion.  

 Reading this article should take approximately 15 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Reading: The Astrophysical Spectator Issue 1.1 (October 2004): “Hydrogen Fusion” Link: The Astrophysical Spectator Issue 1.1 (October 2004): “Hydrogen Fusion” (HTML)

    Instructions: This article discusses the hydrogen fusion reaction in more detail than the previous reading.  It treats both the proton-proton chain and the carbon-nitrogen-oxygen cycle.  Both have the same end result, the loss of four protons and the production of a helium-4 nucleus, two positrons, two neutrinos, and energy.  Focus your attention on the proton-proton chain as it is the one that is most important in our sun.

    Reading this article should take approximately 20 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

11.3 The Evolution of Low Mass Stars   11.3.1 The Production of Carbon and Oxygen   - Reading: The Astrophysical Spectator Issue 2.32 (September 21, 2005): “Fusion of Helium” Link: The Astrophysical Spectator Issue 2.32 (September 21, 2005): “Fusion of Helium” (HTML)

 Instructions: This article is more comprehensive than we will need.
 Focus on the first section, “Alpha Fusion Chain.”  

 Reading this article should take approximately 10 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Reading: University of Oregon: James Schombert’s “Red Giant Evolution” Link: University of Oregon: James Schombert’s “Red Giant Evolution” (HTML)

    Instructions: This article goes into more detail than is needed for this course.  Read the sections up to “Horizontal Branch Stars” carefully.  Of course, read on if you find this interesting.  It will take you through several post-red giant phases of evolution in low-mass stars.  The very end of the reading will introduce you to the evolution of high-mass stars.

    Reading this article should take approximately 10 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

11.3.2 The Death of Low Mass Stars   - Reading: Lawrence Livermore National Laboratory’s Fusion Energy Education: “Planetary Nebulae” Link: Lawrence Livermore National Laboratory’s Fusion Energy Education: “Planetary Nebulae” (HTML)

 Instructions: This article discusses planetary nebulae and has an
image of one that serves as a useful illustration.  

 Reading this article should take approximately 10 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Reading: YouTube: National Aeronautics and Space Administration’s “Planetary Nebula: A New Twist” Link: YouTube: National Aeronautics and Space Administration’s “Planetary Nebula: A New Twist” (YouTube)

    Instructions: This video focuses mostly on the structures of planetary nebulae.  It has some beautiful Hubble Space Telescope images.

    Watching this video should take approximately 5 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

11.3.3 White Dwarfs   - Reading: University of Oregon: James Schombert’s “Planetary Nebula Phase” Link: University of Oregon: James Schombert’s “Planetary Nebula Phase” (HTML)

 Instructions: As with some previous articles, this goes into more
detail than is needed for this course.  Read the sections up to Nova
carefully.  Of course, read on if you find this interesting.  It
discusses the phenomena of nova in some detail, a topic we do not
cover in this course.  

 Reading this article should take approximately 15 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Web Media: Astrophysics Science Project Integrating Research & Education: “Star Life Cycle” Link: Astrophysics Science Project Integrating Research & Education: “Star Life Cycle” (HTML)

    Instructions: This is a very informative and interesting sequence of activities that will help you understand the life cycle of low-mass stars and the H-R diagram in particular.  There are seven sets of activities: one on protostars, three on stars, and three on the H-R diagram.  Go through each one carefully and thoroughly.

    Exploring these exercises should take approximately 45 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

11.4 The Evolution of High Mass Stars   11.4.1 The Production of Elements Up to Iron   - Reading: Castle Rock High School: Carl Stello’s “Evolution of High-Mass Stars” Link: Castle Rock High School: Carl Stello’s “Evolution of High-Mass Stars” (HTML)

 Instructions: This article discusses heavy element fusion and the
death of a high-mass star.  

 Reading this article should take approximately 15 minutes.  

 Terms of Use: Please respect the copyright and terms of use
displayed on the webpage above.
  • Reading: Case Western Reserve University: Chris Mihos’ “Late Stage Nuclear Burning in High Mass Stars” Link: Case Western Reserve University: Chris Mihos’ “Late Stage Nuclear Burning in High Mass Stars” (HTML)

    Instructions: This is a brief description of the nuclear reactions in a high-mass star.  It begins with carbon fusion and goes through to silicon burning.  Do not worry about the specifics of each reaction, just focus on the development of concentric shells of progressively more massive elements.

    Reading this article should take approximately 15 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Reading: Rochester Institute of Technology: Michael Richmond’s “Later Stages of Stellar Evolution in High-Mass Stars” Link: Rochester Institute of Technology: Michael Richmond’s “Later Stages of Stellar Evolution in High-Mass Stars” (HTML)

    Instructions: This article is a comprehensive treatment of the death of a high-mass star.

    Reading this article should take approximately 30 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

11.4.2 Supernovae and the Production of Elements More Massive Than Iron   - Web Media: The Richard Dawkins Foundation for Reason and Science: Neil deGrasse Tyson’s “The Most Astounding Fact” Link: YouTube: Neil deGrasse Tyson’s “The Most Astounding Fact” (YouTube)
 
Instructions: Astrophysicist Dr. Neil deGrasse Tyson was asked the following by a reader of TIME magazine: “What is the most astounding fact you can share with us about the universe?”  His answer is contained in this must-see video.
 
Watching this video should take approximately 5 minutes.
 
Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Reading: Oracle ThinkQuest: “High Mass Stars” Link: Oracle ThinkQuest: “High Mass Stars” (HTML)

    Instructions: This is a very brief description of the evolution of a high-mass star.

    Reading this article should take approximately 5 minutes.

    Terms of Use: Please respect the copyright and terms of use displayed on the webpage above.

  • Reading: National Aeronautics and Space Adminsitration, Chandra X-Ray Laboratory: “Crab Nebula” Link: National Aeronautics and Space Adminsitration, Chandra X-Ray Laboratory: “Crab Nebula” (PDF)

    Instructions: This article discusses the history of the Crab Nebula supernova. It also talks about the neutron star (pulsar) at its center.

    Reading this article should take approximately 15 minutes.

    Terms of Use: This article has been reposted for non-commercial, educational purposes. It is attributed to the National Aeronautics and Space Administration, and the original version can be found here.

  • Assessment: The Saylor Foundation’s “Unit 11 Assessment” Link: The Saylor Foundation’s “Unit 11 Assessment” (PDF)

    Instructions: When you have finished the entire unit, please complete this assessment without referring to the readings.  When you are finished with the assessment, you can check your answers against the Saylor Foundation’s “Unit 11 Assessment – Answer Key” (PDF).

    Completing this assessment should take approximately 2 hours.