Abstract

Nearly all of the quantitative information we have about the cosmos is the result of spectroscopy, the science of using spectra to make physical measurements. We can directly measure the temperature, density, pressure, or composition of a cloud of gas or a star, using a telescope and a spectrometer. The spectrum forms in highly non-equilibrium gas and dust. Analytical theory cannot be used to understand the conditions so numerical simulations are required. Cloudy is a code that does this - it calculates the ionization, chemistry, radiation transport, and dynamics simultaneously and self consistently, building from a foundation of atomic and molecular processes. The result is a prediction of the conditions in the material and its observed spectrum. These predictions depend on detailed atomic and molecular processes, a complication, but is also why the spectrum reveals so much about its source. We will cover observation, theory, and apply Cloudy to a wide variety of astronomical environments, including the interstellar medium, AGB stars, Active Galactic Nuclei, Starburst galaxies, and the intergalactic medium. The sessions will consist of a mix of textbook study, using Osterbrock & Ferland, Astrophysics of Gaseous Nebulae and Active Galactic Nuclei, and application of Cloudy to research problems chosen by participants. No prior experience with Cloudy is assumed, although participants should have a reasonable knowledge of undergraduate-level spectroscopy and atomic physics. Participants will break up into small teams and organize research projects of mutual interest.