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A technique used by astronomers that allows them to determine the properties, such as composition, temperature, and motion through space, of celestial objects by analyzing the spectra of celestial objects. For example, because each atomic element absorbs and emits light in a unique set of wavelengths, the astronomer can sift through the spectrum of a star and determine what elements are present in the star’s atmosphere. From the shapes and depths of spectral lines, the astronomer can calculate fundamental qualities of a star, such as how fast the gases churn through the stellar atmosphere or the star’s effective temperature. An astronomer may also be interested in correlations between the abundances of certain elements and the physical behavior of the star, the age of the star, or the abundances of other elements. For instance, compared with the Sun, stars with low amounts of iron are also low in almost every other element with respect to hydrogen. Spectroscopy is performed by astronomers with instruments called spectrographs.

Featured Images

Backlit Planet September 16, 2016

Hobby-Eberly Telescope at McDonald Observatory

Searching the Darkness October 15, 2010

Radio Programs

Sheratan The hidden nature of a binary star October 24, 2015

Cat’s Eye Nebula The true nature of a glowing cat’s eye August 28, 2014

Anders Angstrom Scanning the “barcode” of the Sun August 12, 2014

Companionship Looking for stellar companions May 28, 2014

Annie Jump Cannon II Classifying the stars December 10, 2013

Castor Three sets of stellar twins January 14, 2013

More Capella Seeing a star in a different light December 6, 2012

Messengers The messengers of the stars February 1, 2011