Metallic line profiles in cepheid variables

A grid of synthetic line profiles incorporating a new treatment of macroturbulence is calculated for a Cepheid atmosphere in radial motion. Projection factors are determined to be up to 10 per cent higher than previous calculations. A relationship is found between the asymmetry of the line profiles and γ, the ratio of pulsational velocity to line half-width at half-height. A programme of high-resolution spectroscopic observations of Cepheids has been carried out at Mt John University Observatory for several years. Radial velocities and asymmetries have been measured for selected metallic lines and the asymmetries compared with those of the synthetic profiles. The line profiles from the observations show a larger asymmetry than the synthetic profiles at phases of inward pulsational velocity. The asymmetry at phases of outward velocity is smaller and in agreement with the synthetic profiles for some Cepheids. However, for others the asymmetry at phases of outward pulsation is in the dire

A grid of synthetic line profiles incorporating a new treatment of macroturbulence is calculated for a Cepheid atmosphere in radial motion. Projection factors are determined to be up to 10 per cent higher than previous calculations. A relationship is found between the asymmetry of the line profiles and γ, the ratio of pulsational velocity to line half-width at half-height. A programme of high-resolution spectroscopic observations of Cepheids has been carried out at Mt John University Observatory for several years. Radial velocities and asymmetries have been measured for selected metallic lines