Modern astronomy has its roots firmly grounded in the fundamental principles of physics (classical and modern), and correspondingly, many branches of physics as we know them today trace their origins to the search for universal physical laws to explain natural phenomena discovered and analyzed by astronomers.

The goal of theoretical astrophysics is to provide physical and conceptual understanding of the diverse systems that represent our universe. Introductory astronomy courses are often organized by scale (planets, stars, galaxies, and the universe...), and observational astronomy courses are often organized by wavelength because of detector technology. To emphasize the different approach needed for developing a theoretical framework, this course is organized into themes of governing physical processes. For each of three main themes (gravitational physics, gas physics, and quantum physics), we will start with fundamental principles, and then discuss applications in various astronomical contexts. We will also discuss systems in which several physical processes interact synergistically, and demonstrate how astrophysical theories are developed by successive model refinements and confrontations with data. We will show how application of simple physical laws can explain the observed properties of an astounding range of astronomical objects!

An important aspect of this course will be to use astrophysical examples to develop flexible problem-solving skills: how to approach questions when you don't know in advance what tools you need to solve them, and how to exercise quality control by being your own critic.

Topics may include:

Gravity:
planetary and binary orbits, Lagrange points, tidal forces and the Roche limit, epicyclic approximation, dynamics of clusters:  dynamical friction and relaxation, the Virial theorem, potential/density pairs, orbit families and galactic structure

Gas physics:
thermodynamic and statistical gas properties, fluid dynamics equations, hydrostatics: atmospheres of stars and planets, polytropes, ISM clouds, circumstellar disks, convective instability in stars, gravitational (Jeans) instability, thermal radiation, cosmological evolution

Quantum physics:
quantum fundamentals, particle in a box, Fermi and Bose statistics, uncertainty principle and Pauli exclusion, degenerate stars - limiting masses, Hydrogen atom structure and spectra

Model Synthesis:
matter/radiation interaction, nuclear reactions, diffusive processes, stellar structure and explaining the H-R diagram

This course is intended for astronomy or physics majors or other students with strong physical science background. Physics courses through Phys 273, and ASTR 120/121 or 200 are prerequisites. With permission of the instructor, some prerequisites may be waived.