Presentation #103.48 in the session Missions and Instruments.
High energy emission lines provide a unique probe of the physics of cool stars. This is especially true for active stars which have very complex multi-temperature coronae with stochastic flares. Young stars are a subset of active stars which include activity induced via accretion which can be both steady state and episodic. This emission can be the driving force on the atmospheric evolution of planets around these stars. The spectroscopic lines seen when observing these stars can be used as diagnostics of the local temperatures and densities. These lines include: CIV, OVII, OVIII, NeIX and NeX in the soft X-ray as well as CII (multiplet), CIII (multiplet), CIV, OVI (doublet), and NV (among others) in the FUV. Together these lines allow us to model a fairly complete picture of the stellar activity for a given star and from there we can model the impact on any orbiting planet. The Arcus Probe combines high-resolution, efficient, lightweight x-ray gratings with silicon pore optics to provide soft x-ray spectra (10-50 Å) with R~3500 and a large average effective area (~500 cm2), an order of magnitude larger than the Chandra gratings. In addition, Arcus probe features a high resolution UV spectrograph operating in the range of around 1000-1600 Å.