The Influence of Active Regions on Plasma Flows Inside the Sun

When (times in MT)
Wed, Oct 25 2023, 2pm - 1 hour
Event Type
Sushant Mahajan
Stanford Univ.

In this talk, I will explore recent advancements in the study of how active regions modulate plasma flows within the Sun. The processes responsible for the magnetic field amplification within the Sun, which ultimately give rise to active regions, are anticipated to have an impact on the Sun's internal flow patterns. By analyzing global helioseismic measurements of the Sun's time-varying rotation rate, we have identified patterns that correspond to the theoretically expected signatures of magnetic field amplification deep within the solar convection zone. As active regions emerge on the solar surface, they exert influence on plasma flows in their vicinity, inducing surface inflows toward their centroids and deeper outflows. Through local helioseismic observations of surface flows, we quantify the extent to which active regions contribute to the modulation of the global meridional flow and differential rotation via these inflows. Pinpointing the locations of magnetic field amplification within the solar interior is of paramount importance for validating numerical models and confirming our understanding of magnetic field amplification process(es). Simultaneously, characterizing the near-surface inflows around active regions plays a vital role in determining the rate at which polar magnetic fields accumulate towards the end of the sunspot cycle, thus exerting a decisive influence on the amplitude of the forthcoming sunspot cycle.

About the Speaker

Dr. Sushant Mahajan is a Postdoctoral Fellow at the Hansen Experimental Physics Lab, Stanford University, currently working with the Helioseismic Magnetic Imager (HMI) Science team. He is also an active collaborator in the NASA Drive Science Center: COFFIES (Consequence of Flows and Fields in the Interior and Exterior of the Sun) and volunteers some of his time at the Wilcox Solar Observatory to keep it running. Sushant completed his PhD in 2019 from Georgia State University, with a thesis on "Observational constraints on the solar dynamo and the hunt for precursors to solar flares". Post his PhD, he spent two years on Maui as a postdoc at the Institute for Astronomy, University of Hawaii and later moved to Stanford University in 2022. Sushant analyzes helioseismic data to characterize the interactions between magnetic fields and plasma flows in the solar interior. He has experience working on the development of feature tracking algorithms, numerical models of the solar dynamo as well as preparing and utilizing machine-learning-ready datasets for forecasting solar flares.