The Secret Lives of Cepheids: Exploring Cepheid X-ray Activity and Variability

We propose an XMM observation of the prototype of Classical Cepheids delta Cepto confirm Xray variability. The data will complement our existing XMM data andHST FUV spectroscopy for this important star with welldefined, phasedvariability from 10,000 300,000 K plasmas, originating from pulsationinducedshocks. We request one 65ksec exposure of delta Cep to confirm enhanced Xrayactivity around 0.5p, observed in our previous XMM data. If confirmed, thephasing of the Xray activity will stand in stark contrast to that of the FUVemissions, and provide important information on the atmospheric heatingmechanism(s) of this Cepheid. We also propose a 40ksec observation of theCepheid zeta Gem to search for Xray activity and expand the current Cepheid Xray Inventory. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]