Variations in the strength of spectral features in spheroidal galacticsystems. I. The method and CN band variation.

Moderate-resolution, high signal-to-noise spectra of elliptical galaxies are used to study the relation of the strength of the CN bands to other properties of the Galaxy. A new technique for the measurement of the strength of spectral features is described. Galaxy spectra are divided, pixel by pixel, to reveal subtle differences without loss in spectral resolution. Large intergalaxy CN variations are seen. Further, the CN band strength is shown to be not well correlated with either the strength of other spectral features or with the total luminosity. Two tentative explanations for this effect are proposed.