Cepheids\: Unraveling Mass Loss and Luminosity

The Cepheid Leavitt law (PL relation) continues to be a cornerstone ofcosmology. However, the favored implementation in the infrared requires anunderstanding of CircumStellar Envelopes (CSEs) seen around many Cepheids. CSEsmay also hold the key to possible pulsation driven massloss, an importantcomponent evolutionary modeling. Recently discovered Xray bursts modulated bythe pulsation cycle provide a possible link to CSEs. The observations requestedhere will test the link between Xrays and CSEs (Eta Aql), and also theconnection to the atmosphere collapse Xray trigger (Zeta Gem). truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]