The evolving magnetic lives of young Suns

This is a coordinated HST+XMMNewton program to address the conditions thataffect habitability on Earthlike planets around Sunlike stars. Both wavelengthregimes (farUV with HST, Xrays with XMM) are needed to constrain modelssufficiently to represent realistic conditions. An approved TESS program for ourtargets will provide additional information on surface inhomogeneities (spots)and their sizes and locations so that that can be taken into account as well.The FUV and Xray fluxes from young stars are erosive of a planet.s atmosphere,particularly for hydrogen, but also for oxygen and nitrogen, both chemicallyimportant elements. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]