Spring 2016 Astronomy 242 M,W,F 10:30 — 11:20

ASTR 242 is a calculus-based introduction to stellar, galactic, and extragalactic astrophysics. In this course, basic concepts of classical mechanics, thermodynamics, E&M, and modern physics are used to understand the structure and evolution of stars, galaxies, and the Universe. ASTR 242 is the second course in a sequence leading to a astrophysics major.

Time & Place: Monday, Wednesday, Friday, 10:30 — 11:20 in Watanabe 114

Professor: Joshua E. Barnes (barnes at
Office: Institute for Astronomy, Room C-219 (956-8138)
Office hours: MF 10:00 — 10:20 in Wat. 114, 11:30 — 12:00 in Wat. 423, or by appointment

Teaching Assistant: Kelly A. Blumenthal (blumenthal.kelly at
Office hours: F 9:00 — 10:30, 12:30 — 2:00 in Watanabe 403, or by appointment

Text: Foundations of Astrophysics by Barbara Ryden & Bradley M. Peterson

Astronomy help: See any Astronomy TA in Watanabe 403; hours are posted outside

Course Outline & Schedule

Dates Topic   Reading
01/11 01/13 01/15 Stellar Parameters. I Distance scale; Luminosities, fluxes, magnitudes, colors; Atmospheric structure; Spectral lines; Temperatures 13.1, 13.2, 13.3, 14.1, 14.2
  01/20 02/22 Stellar Parameters. II Binary Stars; Masses; Radii; Hertzspring-Russel diagrams 13.4, 13.5, 14.3, 14.4
01/25 01/27 01/29 Interstellar Medium ISM phases; Dust, reddening; Neutral Hydrogen, 21 cm line; Molecular clouds; Ionization nebulae 16
02/01 02/03 02/05 The Milky Way MW overview; Disk kinematics; Star clusters; Stellar populations; Galactic center; Dark halo 19
02/08 02/10 02/12 External Galaxies Galaxy classifications; Galaxy masses; Scaling relations; Distances 20
  02/17 02/19 REVIEW & MIDTERM
02/22 02/24 02/26 Galactic Evolution Galactic populations; Passive evolution; Collisions; Black holes; Active Galaxies 21
02/29 03/02 03/04 Mapping the Universe Hubble's law; Clusters, groups; Intercluster medium; Large-scale structure; High-redshift galaxies 22
03/07 03/09 03/11 Cosmological Models Expansion of the Universe; Newtonian & relatavistic models; Friedmann equation 23
03/14 03/16 03/18 The Big Bang Cosmic background radiation; Flatness & horizon problems; Inflation; Big bang nucleosynthesis 24
03/28 03/30 04/01 REVIEW & MIDTERM
04/04 04/06 04/08 Stellar Structure Energy transport; Energy generation; Equations of stellar structure; Stellar models 15
04/11 04/13 04/15 Stellar Evolution Star formation; Main-sequence stars; Advanced nuclear burning; Giant stars 17
04/18 04/20 04/22 Stellar Remnants Degeneracy pressure; White-dwarf stars; Core-collapse supernovae; Neutron stars; Black holes 18
04/25 04/27 04/29 Origin of the Elements Abundances of elements; White-dwarf supernovae; Neutron capture; Chemical evolution
05/02 05/04   FINAL REVIEW

Learning Objectives

This course introduces students to key aspects of modern astrophysics, including the history and large-scale structure of the universe, the nature and physics of galaxies, and the structure and evolution of stars. Students will learn to apply Newtonian dynamics on galactic and extragalactic scales, and to evaluate evidence for unseen matter. They will be able to summarize the key parameters of modern cosmological models and calculate their properties. They will understand and apply the key ideas of stellar structure: hydrostatic equilibrium, energy transport via radiation and convection, and nuclear energy generation.

This course aligns with a number of UH Manoa's Institutional Learning Objectives, including: objective 1a (general understanding of the Universe), objectives 2a (critical and creative thinking, problem solving, mathematical reasoning) and 2c (collaborative work with peers), and objectives 3a (intellectual curiosity) and 3c (respect for resources).

Discussions, Problem Sets, Exams, & Grades

Friday class sessions will be devoted to classroom discussion, with an emphasis on problem-solving. To motivate the discussion, a problem set will be distributed at the start of each week. These problems will be discussed by the class as a whole and by students working in small groups. The objective is to insure that all students know how to solve the assigned problems.

Written solutions to the problems will be due the following Monday at the start of class. Late work must be handed in by Wednesday, and will receive 70% credit. Work will be graded and returned to the class on Friday.

There will be two midterm exams, on 02/19 and 04/01. Review classes will be given before each exam. The final exam will be given from 9:45 to 11:45 on 05/13 in Wat. 114. The final is cumulative.

In-class participation, problem sets, midterms, and the final are worth 20%, 30%, 25%, and 25%, respectively. You must take the final to receive a passing grade.

Joshua E. Barnes      (barnes at
Updated: 23 January 2016
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