Spectrophotometric studies of CO Cephei

Abstract

Spectrophotometric and spectroscopic observations of CQ Cep, the shortest-period binary with a WN component, are presented. Excepting the N V 4603 A, the fluxes of all other emission lines show enhancement at minima. They can be explained by the Roche surfaces that take into account the strong wind of the WN7 component. Various radial velocity curves for emission and absorption give different orbital solutions with a general positive shift of gamma axes. Although N IV 4058 A represents the true motion of the WN7 component, its flux variations are influenced by geometric effects. There is no signature of the companion. The extent of the atmosphere of CQ Cephei appears larger than in V444Cyg, another eclipsing binary with a Wolf-Rayet component.