AST 3010H Advanced Topics in Stellar and Galactic Astronomy

Synopsis

Transient stars sometimes appear on the sky. In this course, we will first discuss “transient physics,” the physics we require to understand known types of transients – novae, supernovae, X-ray and γ-ray bursts – and their aftermath, comparing predicted behaviour with observations. Next, we will turn to “possible transients,” systematically exploring what systems could lead to transients, discussing which ones might have possible observational counterparts, and determining how these could be found by the current and next generations of transients surveys. The goal is to produce a complete review of what one might expect, at a level that is useful for transient surveys, and ideally is suitable for publication (if so, by the class as a whole; surprisingly, such a review of expected types of transients does not yet seem to exist).

Transient Physics

• Small Nuclear Runaways: Shell Flashes and Detonations
• Large Nuclear Runaways: He Flash, Carbon Deflagration.
• Sudden Removal of Pressure Support: Electron Capture, Core Collapse, Pair Instability.
• Mergers: Stars, White Dwarfs, and Neutron Stars
• Evolution of Ejecta: Expansion and Radioactive Heating

Possible Transients

We will explore systematically what types of transients one might expect from single stars, binaries, and clusters of stars. We will focus on binaries, checking for any sensible combination of two types of stars how they could interact during their evolution, and what final product one might expect. For a rough sense of the aim, see the outcome grid made by Stephen Justham (KIAA/Beijing).