Exploring Activity Across the Stellar Main Sequence with the Sun as a Benchmark

The active atmospheres of cool main-sequence stars (F-M type) often release a fraction of their stored magnetic energy, producing enhanced emissions (flares) across radio to X-ray wavelengths and associated space weather events like coronal mass ejections (CMEs) and energetic particle events (EPEs). Detailed imaging of active regions and CMEs, and in-situ EPE measurements are possible only in our Sun, making it a benchmark for stellar activity research. Multiwaveband solar imaging datasets let us define robust disk-integrated Sun-as-a-star diagnostics of active region and space weather, extendable to stellar datasets. Radio waveband provide diagnostics of particle acceleration, CMEs and EPEs, essential to model flare events and their space weather impacts. The Square Kilometre Array (SKA) telescopes will facilitate sub-second scale spectropolarimetric imaging of the solar corona across 0.05 - 15GHz, enabling detailed vertical tomographic studies of the active region across a range of coronal heights. Coupled with high energy instruments, the SKA telescopes will allow well-constrained modeling of large samples of diverse active phenomena and the defintion of robust Sun-as-a-star diagnostics of active region and space weather. Besides, the supreme sensitivity and angular resolution of the SKA telescopes will help detect quiescent and active emissions from several nearby stars. This chapter discusses the importance of comparative solar-stellar studies using Sun-as-a-star diagnostics in understanding activity and associated space weather conditions in stars across the cool main-sequence, and presents some research avenues that will benefit solar and stellar astrophysics.