The chemical composition and luminosity of the CH-type cepheid, V553 Centauri.

V553 Cen is found to be deficient in elements heavier than helium by about a factor of five. No marked excess of carbon is present, but the uncertainties allow it to have a sufficient carbon excess to explain the strong CN, CH, and weak C2 seen in the spectrum. The s-process elements Ba and La are not enhanced by more than about a factor of two, relative to iron. The absolute visual magnitude is found to be near -0.5, which is consistent with a disk-type Cepheid with a period of two days.