An Etymological Dictionary of Astronomy and Astrophysics

The strength of the → calcium break, as measured from the fluxes in the intervals 3750-3950 Å and 4050-4250 Å. It is given by the expression Ca-break[%] = 100 · (f_upper - f_lower)/f_upper,
where f_upper and f_lower are the mean fluxes measured in the 3750-3950 Å and 4050-4250 Å bands, respectively,
in the rest frame
(Dressler & Shectman 1987, AJ 94, 899).

See also: → calcium; → break; → index.