The internal electronic structure of each type of atom consists of discrete energy states, and these states are unique to that type. The figure below shows part of the spectrum of the Sun at yellow wavelengths. The dark lines are produced by atoms of magnesium, iron, titanium, and other elements. Quantitative analysis of such spectra tells us the detailed chemical makeup of the Sun and other stars. In addition, spectra also contain information on the velocity, pressure, density, temperature, ionization state, magnetic field strength, and other physical characteristics of cosmic objects.
Spectroscopy is therefore an exceedingly powerful tool.
It is the source of much of the astrophysical information we have about the universe. Download, print, and read the webnotes for this lecture. Review the reading assignments in the ASTR 130 Manual. You should be working on Labs 3 and 4 and the first optional lab. All rights reserved.