An Arcus view of stellar space weather.

Arcus is a Medium Explorer (MIDEX) NASA mission to be proposed near the end of 2021. One of the three science goals for Arcus is to explore how stars, circumstellar disks, and exoplanet atmospheres form and evolve. The mission provides high‐resolution, soft X‐ray spectroscopy with required effective area EA=220$$ EA=220 $$ cm2 and resolving power R=2500$$ R=2500 $$. Key science topics discussed here are the structure and heating of stellar coronae across the HR diagram and magnetic accretion onto young stars. These studies will contribute to our understanding of the impact of stellar space weather on exoplanet atmospheres. [ABSTRACT FROM AUTHOR]