Variations of POP. II Cepheid UV Energy Distributions
Abstract
We want to observe the changes of the ultraviolet energy distribution of the population II Cepheid kappa Pav and the suspected population II Cepheid SZ Tau. The observations of the continuum energy distributions will give us log Z/Z(sun) and the change in Teff as a function of pulsational phase. We would also like to follow the properties of the outward moving shock by observing the changes in the emission lines. For the previously observed population II Cepheids ST Pup and W Vir, we saw emission lines develop shortly after maximum light. No more observing time was available to follow the changes. For the bright Cepheids kappa Pav and SZ Tau we will be able to follow the evolution of these emission lines. The ratio of the SiIII] to CIII] lines at 1892 and 1909A (both observed in ST Pup and W Vir) will give us the change in densities for the outward moving shock. Perhaps we will be able to determine rough values for the velocities and in that way probe the outer atmospheres of the Cepheids.
- Publication:
-
IUE Proposal
- Pub Date:
- July 1984
- Bibcode:
- 1984iue..prop.1768B