The Secret Lives of Cepheids: Exploring the X-ray Variability of delta Cep

We propose XMMNEWTON EPIC observations of the prototype of Classical Cepheids,δ Cep, that we discovered is a variable Xray and FUV emissionline star.The data will complement existing / approved HST FUV spectroscopy and completeXray phase coverage for this important star, which shows welldefined phasedchanges of FUV emission line fluxes from hot (10,000 300,000 K) plasmas. Theemissions peak between pulsation phases 0.75 1.05 and likely originate frompulsationinduced shocks. We request two 90 ksec exposures of δ Cep,covering the critical phase range of virgul0.5 1.0, where Xray emissions shouldpeak. These phases were not previously covered by XMM. The requestedobservations will provide crucial tests of atmospheric heating theories for Cepheids. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]