Ian J. M. Crossfield
KU Physics & Astronomy Dept.
Lawrence, KS 66044
email : ianc@ku.edu

ASTR 391 -- Spring 2026

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• Syllabus, schedule, and other docs
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Syllabus and schedule

• Syllabus (PDF) <-- This has all the details you need!

PSets and solutions

No.	Topics	Pset	Due	Solutions
Zero	Start-of-course survey	Pset	Jan 23
	Draft CV/Resume -- RUBRIC HERE		Jan 28
01	Forces, Introductory Concepts, and Estimates	Pset	Feb 2
	3 Possible Research Paper Topics		Feb 4
	Class Visit to Silent Sky (at Free State High Theatre)		6:40pm, Feb 5
02	Parallax, angular scales, stars.	Pset	Feb 9
	Final CV/Resume		Feb 11
03	Binaries, stars, and planets.	Pset	Feb 16
04	Nuclear reactions and Stellar Evolution	Pset
05	Stellar Interiors	Pset
06	Radiation	Pset
07	Galaxies	Pset
08	AGN and the Universe	Pset
	Final research paper due. Everything else due. All late/regrades due.		May 6

Course Outline

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No.	Date	Topic and/or Reading Selections	Lecture Notes
1 - W1L1	2026/01/21	Introduction to astronomy. Orders of magnitude; magnitudes. Types of objects and observations.	Lecture Notes (PDF), lecture slides.
2 - W1L2	2026/01/23	CVs and Resumes (guest lecture)
3 - W2L1	2026/01/26	Intro to astrophysics. Common quantities, forces, and particles.	Lecture Notes (PDF)
4 - W2L2	2026/01/28	Common quantities and concepts.	Ibid.
5 - W2L3	2026/01/30	Parallax, distance and size scales.	Lecture Notes (PDF)
6 - W3L1	2026/02/02	Spectroscopy and Photometry.
7 - W3L2	2026/02/04	Basic properties of stars. Mass, temperature, luminosity. Energy.	Lecture Notes (PDF)
8 - W3L3	2026/02/06	Classification, spectral types. Gray book, Chp. 1-2 -- see below.	Lecture Notes (PDF)
9 - W4L2	2026/02/11-13	Binary star systems. Two-body Keplerian problem. Kepler's Laws.	Lecture Notes 1, Lecture Notes 2
10 - W5L1	2026/02/16	Binaries and Exoplanets.
11 - W5L2	2026/02/18	Observational stellar evolution. "Road Map" and the Hertzsprung-Russell diagram.
12 - W5L3	2026/02/20	Observational stellar evolution: the end states of stars.
13 - W6L1	2026/02/23	Introduction to nuclear reactions	Reading: Lecture Notes (PDF) Choudhuri, Sec. 4.1 Wikipedia (through and including "Energy Conservation"). More detail than you want on nuclear physics (from MIT)
14 - W6L2	2026/02/25	Main nuclear reactions in stars	Reading: Lecture Notes (PDF) Choudhuri, Sec. 4.3 Proton-proton chain reaction CNO cycle reaction Old-timey but informative website on fusion concepts
15 - W6L3	2026/02/27	Stellar evolution: Timescales, overview & final stages	Reading: Lecture Notes (PDF) Lecture Notes (PDF) (a more technical supplement; optional). Lecture Notes (PDF) Choudhuri, Secs. 4.5, 4.6, 4.7 Useful notes on stellar death.
16 - W7L1	2026/03/02	Compact objects: White Dwarfs, Neutron Stars, and Black Holes	Reading: Lecture Notes (PDF) Choudhuri, Chapter 5
17 - W7L2	2026/03/04	Exam review.
W7L3	2026/03/06	Midterm 1

External Readings

• Order-of-magnitude approximations (courtesy of Ned Wright).
• Astronomy Picture of the Day(APOD) -- a venerable and always-fascinating daily astronomy vignette.
• Freedman et al., Intro to Astronomy, Chapter 1.
• Freedman et al., Intro to astronomical magnitudes, Chapter 17.
• Bennett et al., Intro to Astronomy, Chapter 1.
• "History of Stellar Spectral Classification," Gray & Corbally, Chapter 1.
• "An Overview of Normal Stars," Gray & Corbally, Chapter 2.
• Goldstein et al., on the Two-Body Problem
• UCLA Galactic Center Group: Orbital Animations
• Binary systems:
  • Caroll & Ostlie on Binary Systems
  • Holberg et al. 2007, The Discovery of the Companion of Sirius
  • Shahbaz et al. 1994, The mass of the black hole in V404 Cygni
• Overview of Recent Exoplanet Progress
• Rybicki et al., on Intro to Radiation, first half of chapter 1.