An Etymological Dictionary of Astronomy and Astrophysics
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A mathematical function that describes how the → intensity  I of a → galaxy varies with distance R from its center. It is given by: (dln I/dln R) = -(b/n)(R/R_e)^1/n. The constant b is chosen such that R_e is the → effective radius; n is the Sérsic index. The Sérsic profile is a generalization of → de Vaucouleurs law. Setting n = 4 gives the de Vaucouleurs profile.

J. L. Sérsic, 1963, Boletin de la Asociacion Argentina de Astronomia, Vol. 6, p.41; → profile.