LASP Science Seminars

Stellar activity drives space weather, influencing planetary atmospheres and habitability. The Sun is the only known star to host a biosphere, though in general cool main-sequence stars (F – M type) host the majority of Earth-like exoplanets. Hence, to address the fundamental questions of whether our Sun is a unique host star, if life can exist elsewhere given the host stellar activity, and what planetary properties are important to shield against a typical sun-like star’s activity, we need comparative studies of the nature of quasi-steady and flaring activity across the cool main-sequence stars with the sun as a template. Stellar activity emerges due to various dynamical phenomena across the chromosphere to the corona. Millimeter-to-radio (Sub-terahetrz)  frequencies probe varying heights across the chromosphere to the corona facilitating a tomographic exploration of the active atmospheric layers. Sensitive modern sub-terahertz interferometers let us perform <~ 1s scale imaging tomography in the Sun and cool stars. In this talk, I will present our recent results and discoveries using sub-terahertz imaging tomography. I will present novel insights into the evolution of solar active regions into a flare phase and the discovery of solar-type radio bursts commonly found during fast solar-CMEs in a non-solar type young M dwarf. I will present our results comparing the chromospheric activity of the sun and cool stars using mm imaging observations that provide insights into the rise of activity in the main sequence.