Joint Astrophysics/Space Physics Seminar - Professor Kenneth Gayley, Department of Physics & Astronomy, The University of Iowa
"How A Spectral Line Carries Energy and Information” by Professor Kenneth Gayley, Department of Physics & Astronomy, The University of Iowa
Abstract: It has been said that if a picture is worth a thousand words, then a spectrum is worth a thousand pictures. Astronomers know that optically thick spectral lines in stars like the Sun have been crucial for our understanding these objects, and they are also important coolants for stellar chromospheres. Students are usually taught "Kirkhoff's laws" for interpreting absorption and emission lines, but actually the logic of a spectral line involves more specific and more powerful rules that are less widely understood. This seminar is aimed at conveying those more powerful, yet still relatively simple, rules, by which we can understand how optically thick spectral lines convey both energy and information from a stellar atmosphere to its environment.