Astronomy 205a

Instructor: Professor Stephen Boughn, ext. 1146

Textbook: Foundations of Astrophysics by Ryden and Peterson. We will cover much of the first 18 chapters of the text (excluding Chapter 16). The remainder of text will be covered in Astro 206. Undoubtedly, this book will prove to be a valuable reference resource for those of you who choose to major in astronomy or astrophysics.

Reference Material: Several other introductory astronomy and astrophysics texts will be placed on reserve in the Strawbridge Observatory Library and, of course, the library is filled with books on the subject. Don't hesitate to use them, especially if you find a particular section in your text difficult to follow. Occasionally, readings from the reserve texts will be assigned.

Observatory Keys: In order to have access to the library and the telescopes after hours, it will be convenient for you to have a key to the Observatory. You will be issued a key shortly after the beginning of the semester.

Course Description: Astronomy 205a is the first half of a two-semester sequence (Astro 205a and Astro 206b) required for astronomy and astrophysics majors. The first semester is devoted to the study of stars, the premier residents of the universe, and the planets of our solar system. Both of these topics involve important physical concepts and so relevant topics in physics will be introduced. This is the “physics” in “astrophysics.” Together with Astro 206b (Galactic and extragalactic astronomy, and cosmology), this course will provide a broad introduction to astronomy and astrophysics and serves as a prerequisite for the study of advanced topics. About 2/3 of the course will be devoted to the study of stars and the remaining 1/3 to the solar system. Another goal of Astro 205a is to provide an introduction to observational astronomy. This goal will be addressed by completing three observing projects on the order of one every 4 weeks. These will require some additional instruction in the use of telescopes during the first few weeks of class (see below).

Assignments, Projects, and Exams: Written homework assignments will be due every two weeks. Collaboration on homework assignments is encouraged except on those problems where it is explicitly forbidden. Homework assignments are typically worth 30 to 40 points and a late penalty of 1 point per day (weekends excepted) will be assessed for late homeworks. Short, in-class quizzes on the reading assignments will be given every week. There will be two exams, one on stars and stellar astronomy and the other on star formation, planets, and the solar system. Written reports will be required for two of the observing projects. Course grades will be determined from performance on homework and quizzes (approx. 40%), exams (approx. 35%), and projects (approx. 25%).

Workshops: Several one-hour workshops on telescope use and on project reports will be scheduled during the semester.

Projects: Three observing projects will be assigned during the term. Written reports will be required for projects 2 and 3. The first project will begin the second week of class. Students will work in teams of three at the telescope. After being checked out on the telescope, students are allowed to sign up for independent use of the telescope as long as they are accompanied by another qualified observer. WARNING: The weather is a formidable foe. Even though the actual number of hours you spend observing will be few, you will have to be "on call" for much of the semester. You must be willing to give observing top priority on clear evenings. Otherwise, you won't be able to complete this part of the course.

  1. Observing with the 12” Schmidt-Cassegrain Telescope: You will observe a variety of astronomical objects during the semester and submit a brief (one or two sentence) description of each of your observations.
  2. Sun: A solar telescope will be used to measure solar limb darkening. An analysis of this data will enable you to deduce the temperature gradient at the surface of the sun (photosphere). In addition, observations of the apparent movement of sunspots will be used to determine the sun’s rotation rate.
  3. Stellar Photometry: B and V band photoelectric photometry will be used to measure the light curve of a Cepheid variable. An analysis of this data will enable you to estimate the luminosity of and the distance to the star.

Tentative Course Outline

Topic Reading
Week 1 Radiation Spectra and Telescopes Chapters 5 and 6
Week 2 The Sun Chapters 5 and 7
Week 3 Stars Chapters 13 and 14
Week 4 Stars and Binary Systems Chapters 13 and 14
Week 5 Stellar Structure Chapters 14 and 15
Week 6 Stellar Structure Chapter 15
Fall Break
Week 7 Star Formation and Stellar Evolution Chapter 17
Week 8 Stellar Evolution and Degenerate Stars Chapters 17 and 18
Week 9 Midterm Review/Degenerate Stars Chapter 18
Week 10 Solar System Chapter 8
Week 11 Earth and Moon Chapter 9
Week 12 The Planets Chapter 10
Week 13 Small Bodies in the Solar System Chapter 11
Week 14 Formation of the Solar System and Exoplanets Chapter 12